Case Study Report Fix Banget Inggris (repaired).docx

THE ANALYSIS OF BELT SLIP WEIGHFEEDER 534-WF2

PNJ-PT HOLCIM INDONESIA

CASE STUDY REPORT

BANDAR ZULFIAN NIM : 5216220067 WISNU AGUNG SETIAJI NIM : 5216220222

STATE POLYTECHNIC OF JAKARTA-EVE HOLCIM INDONESIA MAJORING IN MECHANICAL ENGINEERING CONCENTRATION OF ENGINEERING INDUSTRY CILACAP 2018

THE ANALYSIS OF BELT SLIP WEIGHFEEDER 534-WF2

PNJ-PT HOLCIM INDONESIA

CASE STUDY REPORT

BANDAR ZULFIAN NIM : 5216220067 WISNU AGUNG SETIAJI NIM : 5216220222

STATE POLYTECHNIC OF JAKARTA-EVE HOLCIM INDONESIA MAJORING IN MECHANICAL ENGINEERING CONCENTRATION OF ENGINEERING INDUSTRY CILACAP 2018

ii

THE ANALYSIS OF BELT SLIP WEIGHFEEDER 534-WF2

BANDAR ZULFIAN NIM : 5216220067 WISNU AGUNG SETIAJI NIM : 5216220222

Accepted and Approved On 26 July 2018 Advisor I

Advisor II

Arie Setiaji Ibrahim

Fatahula, S.T., M.Kom Assesor I

Drs. Supriyadi Nasution, S.T., M.Kom

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PREFACE

Thanks to God for giving His bounty for preparing a case study report entitled "Analysis of Belt Slip Weighfeeder 534-WF2". And thanks also to the parties who have helped in working on this report. The author chose Weighfeeder 534-WF2 to be used as a case study topic. This report was made to complete a case study based on the curriculum of the Enterprise-based Vocational Education (EVE) education of PT Holcim Indonesia Tbk. And the State Polytechnic of Jakarta in the period of 4th semester. This case study report contains information and causes of Belt Slip on Weighfeeder 534-WF2, such as: engineering process, general design, engineering data, operational parameters, performance, common problems, recommendations, and economic aspects. We expect criticism and suggestions from readers in order to improve this report. We hope this report will be useful to readers. Thanks.

Cilacap, 22 March 2018

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LIST OF CONTENTS THE ANALYSIS OF BELT SLIP ........................................................................... i THE ANALYSIS OF BELT SLIP .......................................................................... ii THE ANALYSIS OF BELT SLIP ......................................................................... iii PREFACE .............................................................................................................. iv CHAPTER I INTRODUCTION ............................................................................. 1 1.1

Background .............................................................................................. 1

1.2

Problem Formation ................................................................................... 2

1.3

Boundary Problem .................................................................................... 2

1.4

Purpose ..................................................................................................... 2

1.4.1

General Purpose .................................................................................... 2

1.4.2

Special Purpose ..................................................................................... 2

CHAPTER II LITERATURE STUDY ................................................................... 3 2.1

Weighfeeder General Knowledge ............................................................ 3

2.1.1.

Function ............................................................................................ 3

2.1.2.

Working Principle ............................................................................. 3

2.1.3.

Equipment Construction ................................................................... 4

2.1.4.

Main Component............................................................................... 5

2.1.5.

Parameter Operasi ........................................................................... 17

2.2

Spesification of Dolomite in Nusakambangan Quarry........................... 18

2.2.1

Main Utility......................................................................................... 18

2.2.2

Characteristic of Material ................................................................... 18

CHAPTER III ....................................................................................................... 19 METHODOLOGY ................................................................................................ 19 3.1

Flow Chart .................................................................................................. 19

3.2

Find Problem .............................................................................................. 20

3.3

Literatur Study ........................................................................................... 20

3.4

Analysis & Problem Solving...................................................................... 21

3.5

Report ......................................................................................................... 21

CHAPTER IV ....................................................................................................... 22

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DISCUSSION ....................................................................................................... 22 4.1

Weighfeeder 534-WF2 ............................................................................... 22

4.2

Specification of Weighfeeder 534-WF2 ................................................... 22

4.3

Location of Weighfeeder 534 – WF2......................................................... 24

4.4

Performance Analysis of Weighfeeder 534-WF2 ( 2017 ) ........................ 25

4.5

Belt Slip...................................................................................................... 27

4.6

Belt Slip in Weighfeeder 534-WF2............................................................ 28

4.7

Root Cause Analysis of Belt Slip in Weighfeeder 534-WF2 ..................... 29 4.7.1

Belt Slack ........................................................................................ 29

4.7.2

Head and Tail Pulley not tight belt properly .................................. 31

4.8

Maintenance Cost Analysis Caused by Belt Slip ....................................... 34

4.9

Production Loss Analysis Caused by Belt Slip .......................................... 37

CHAPTER V......................................................................................................... 38 5.1

Conclusion ................................................................................................. 38

5.2

Solution ...................................................................................................... 38

BIBLIOGRAPHY ................................................................................................. 39

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LIST OF FIGURES Figure 2.1 Equipment Construction of Weighfeeder ............................................... 4 Figure 2.2 Bin in top of Weighfeeder ...................................................................... 5 Figure 2.3 Belt Scale ............................................................................................... 6 Figure 2.4 Speed Sensor .......................................................................................... 6 Figure 2.5 Shear Gate Form ................................................................................... 7 Figure 2.6 Skirtboards............................................................................................. 8 Figure 2.7 Pulleys.................................................................................................... 9 Figure 2.8 Idlers .................................................................................................... 10 Figure 2.9 Bearings ............................................................................................... 11 Figure 2.10 Motor ................................................................................................. 12 Figure 2.11 Gear Reducer ..................................................................................... 13 Figure 2.12 Belt Tensioner .................................................................................... 14 Figure 2.13 Belt Scraper ....................................................................................... 15 Figure 2.14 Strain Gauge ...................................................................................... 16 Figure 2.15 Wheatstone Bridge ............................................................................. 16 Figure 2.16 Load cellon Weighfeeder ................................................................... 17 Figure 3.1 Flow Chart Diagram of Methodology ................................................. 19 Figure 3.2 Data time, amount, dan causes stop in Finish Mill Area ..................... 20 Figure 4.1 Location of Weighfeeder...................................................................... 24 Figure 4.2 Data number of stop in Finish Mill Area ............................................. 25 Figure 4.3 Data stop duration Finish Mill area ..................................................... 26 Figure 4.4 Problem in Weighfeeder ...................................................................... 26 Figure 4.5 Belt Slip Animated .............................................................................. 27 Figure 4.6 Root Cause Analysis ............................................................................ 29 Figure 4.7 Belt Slack Animated ............................................................................ 29 Figure 4.8 Belt tension adjuster ............................................................................ 30 Figure 4.9 Belt tension .......................................................................................... 30 Figure 4.10 Bar damper chute ............................................................................... 31 Figure 4.11 Tail Pulley Weighfeeder .................................................................... 32 Figure 4.12 Rubber Lagging Head Pulley............................................................. 33 Figure 4.13 Material Sticky................................................................................... 33 Figure 4.14 Head pulley Weighfeeder ................................................................... 33 Figure 4.15 Number of repair diagram in 2017 .................................................... 34

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LIST OF TABLES Tabel 2.1 Specification of Weighfeeder ............................................................... 23 Tabel 4.1 Cost maintenance .................................................................................. 35 Tabel 4.2 Cost operational maintenance ............................................................... 36

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CHAPTER I INTRODUCTION 1.1 Background PT. Holcim Indonesia Tbk Cilacap factory is highly dependent on production capacity which is the main target in generating profit. In the cement production process can not be separated also from the performance of a qualified production equipment, not to mention the transport equipment in the Finish Mill area. In Holcim Cilacap Plant there are several types of transport equipment, namely Belt Conveyor, Chain Conveyor, Air Slide, Bucket Elevator, Screw Conveyor, Appron Conveyor, Weighfeeder (Belt Scale) .From all of these equipments are the same except for Weighfeeder (Belt Scale) which has special function and different working principle. Weighfeeder (Belt Scale) is a tool that serves to weigh material and transport material in the cement industry. In PT Holcim Indonesia Tbk. Cilacap Factory, Weighfeeder 534-WF2 functions to weigh and transport dolomite from Dolomite Bin to Belt Conveyor 534-BC4 and then to Ball 564-BM2. During 2017, the amount of stop duration due to the Unschedule Breakdown in the Finish Mill area 2nd lane is dominated by mechanical trouble which reached 297 hours. Where Weighfeeder 534-WF2 ranks third with a duration of hours Breakdown Unschedule of 46 hours. From a brief review to the above problem, the Case Study is focused on mechanical trouble analysis 534-WF2, where the main problem that is analyzed is the cause of belt slip.

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1.2 Problem Formation Based on this background, then the formulation of the problem in thisstudy are as follows: a. the root of the problem on the slip belt in Weighfeeder 534-WF2 b. Impact of belt slip on production process and other equipment. c. Provides an appropriate solution to the root of the belt slip problem in 534WF2. 1.3 Boundary Problem We need to classify the problem into several points in order to elaborate some limits, so that it does not get out of the topic. Here are the issues related to the slip belt problem in 534-WF2: a. Weighfeeder 534-WF2 tool in mechanical and electrical terms. b. Design Weighfeeder 534-WF2. c. Maintenance Proccedure 534-WF2. 1.4 Purpose 1.4.1 General Purpose As one of the requirements to complete the Diploma Program III Department of Mechanical Engineering Polytechnic State Jakarta. 1.4.2 Special Purpose a. Determining the root cause of slip belt on 534-WF2 b. Provide ideas for improvements to improve performance of 534WF2

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CHAPTER II LITERATURE STUDY 2.1 Weighfeeder General Knowledge 2.1.1. Function Weighfeeder (Belt Scale) is a tool that serves to weigh material and transport material in the cement industry. In PT Holcim Indonesia Tbk. Cilacap Factory, Weighfeeder 534-WF2 serves to weigh and transport dolomite from Dolomite Bin to Belt Conveyor 534-BC4 and then to Ball 564-BM2. 2.1.2. Working Principle The material is fed from the chute outlet bin dolomite to the Weighfeeder 534WF2 by opening Pin Gate 534-NG2. The material will flow to the belt weighfeeder and will be weighed while passing through the belt using a load cell sensor. The load cell will provide a signal of the voltage generated according to the weight that will be forwarded to the CCR. This is called static weighing. The static balancing aims to obtain an accurate weight when transported. Unlike static weights, motion or dynamic weighing requires a second input, which is a signal pulse proportional to the speed of the conveyor belt. Each pulse speed sensor belt represents a fixed distance travel. Since the force measured by the load cell is represented as the weight per unit length, it can be multiplied by the distance of the belt journey (one pulse speed sensor) to give the product weight for the belt segment. Example: lbs / ft x ft = lbs The sum of the samples provides a total throughput of product weight across scales. With the right scale (calibration), the total weight takes the measurement unit (pound, ton short, ton long, metric ton, etc.)

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2.1.3. Equipment Construction

Figure 2.1 Equipment Construction of Weighfeeder

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2.1.4. Main Component In Holcim Cilacap Plant there are several types of transport equipment, namely Belt Conveyor, Chain Conveyor, Air Slide, Bucket Elevator, Screw Conveyor, Appron Conveyor, Weighfeeder (Belt Scale) .From all the equipment is the same function except the Weighfeeder (Belt Scale) which has special functions and different working principles. Weighfeeder (Belt Scale) is a tool that serves to weigh material and transport material in the cement industry. In PT Holcim Indonesia Tbk. The Cilacap Factory, Weighfeeder 534-WF2 serves to weigh and transport dolomite from Dolomite Bin to Belt Conveyor 534-BC4 and then to 564-BM2 Ball Mill. a. Silo, Bin and Hopper Applications A rod or pin gate has a series of steel bars sliding inside a rectangular opening. This valve provides full product flow when open, and is ideal for product sizes of 0.5” (12mm) or greater. For applications with a large variance between particle sizes with fine rods that interlock can be used from both sides of the bin discharge for better flow control.

Figure 2.2 Bin in top of Weighfeeder

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b. Scale The belt scale within the weighfeeder requires all the attention to detail that a normal belt scale application requires, however the weighfeeder is designed to be an optimum weighing device with the scale integrated into it. Mounting load cells outside of the weighfeeder frame allows for quick and easy cleaning as well as calibration. Vertical adjustment of the scale allows for easy alignment with the approach and retreat belt supports.

Figure 2.3 Belt Scale

c. Speed Sensor The speed sensor is normally mounted to the driven pulley of the weighfeeder. Return belt mounted versions can also be used, however positive contact and installation space may be a concern. Motormounted speed sensors are also an option, however belt-slip from the drive pulley is not detected with a motor mounted version. An ideal combination is a driven pulley primary speed sensor with a secondary motor mounted sensor to detect belt slip as well as accurately monitor the belt speed.

Figure 2.4 Speed Sensor

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d. Shear gate The shear gate sets the material profile on the belt and bed depth. There are two types of profile for a shear gate: flat and half moon style. The flat type allows for more volumetric capacity on the conveyor belt, but also provides more material contact on the skirtboards which can lead to premature wear and also material bridging. The half moon style shear gate profiles the material so that it has a minimal contact to the skirtboards and also promotes a more consistent flow of material out of the inlet as a flat profile can be unstable or shift as it is conveyed.

Figure 2.5 Shear Gate Form

e. Skirtboards The material containment along the belt is critical to ensure accurate weighing. The skirtboards should be flared out and up from the inlet so that material plugging or jamming does not occur. In applications with materials that can fluidize, skirtboard seals should be added so that spills are avoided at the sides of the belt. The skirtboards should also be designed for compatibility with the material. Caustic materials should be met with stainless steel or coated skirtboards. In applications with abrasive materials skirtboards constructed of AR400 or AR500 steel or with wear plates should be used.

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Figure 2.6 Skirtboards

f. Belt In general, weighfeeder belts should be the endless type for optimum weighing accuracy. An endless belt has a more consistent cross section over its entire length, where belts with a mechanical splice have a singular heavy section which can impact accuracy. An endless style belt requires a cantilevered weighfeeder frame for belt removal. Cantilevered frames and endless belts also provide a faster changeover than vulcanizing in place or mechanical splice belts. Belt PIW rating must be determined by the application considerations such as material bed depth, belt width, conveyor, and inlet length. The PIW rating must be met or exceeded to ensure reliable conveying of the material. The belt PIW rating should not exceed 400, as the belt becomes selfsupporting at that tension rating and will not provide proper deflection for accurate weighing results. Weighfeeder belts are normally supported on flat pans, bars, or idlers so that tension and temperature influences are minimized. Heat dissipation through a belt to electronic components is considered good but the temperature specifications of the belt and of the weighfeeder should not be exceeded. Where possible, actual temperature profiling can provide data for comparison with a high degree of reliability.

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g. Pulleys The pulleys of the weighfeeder should be crowned for positive belt tracking. Drive pulleys must be lagged for consistent conveying without slipping. Driven pulleys do not require lagging, however on short conveyors (<6.5’ (2m) the driven pulley should also be lagged to avoid changes in belt tension due to concentricity. Pulley lagging for wash down applications is typically a food grade neoprene, mineral processing uses a standard SBR lagging. Lagging style and thickness can be per the end user specification; normally it is a minimum ¼” (6mm). Pulleys can be welded to the shaft or use an XT hub for taper locking to a keyed shaft.

Figure 2.7 Pulleys

h. Idlers If the unit uses idlers for belt support, the scale idler and the idler both before and after it must be scale quality. Idlers should meet the CEMA standard for reliable conveying, and proper review of the belt loading will determine what class of idler is needed. Lubricated and sealed for life bearings help reduce maintenance time on the weighfeeder

and

also

provide

excellent

protection

against

contamination and lubricant loss. A flat profile idler is recommended for optimum belt tension and minimizing temperature effects on the

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belt. In some applications, the inlet idlers will require a higher CEMA rating than the carrying idlers after the inlet. Special impact idlers can also be applied under the inlet if long particle drops occur during empty bin filling. An idler must always be located directly under the shear gate and directly under the back of the inlet to provide adequate sealing with the belt. Return belt idlers should be included on any unit that has a pulley-to-pulley distance greater than 10ft (3m). The return idler typically sits inside the belt and does not span the entire width. On corrugated side wall belts, the return idler should allow for belt misalignment and be no more than BW-10” (250mm) in width.

Figure 2.8 Idlers

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i. Bearings The head and tail pulleys are mounted to the weighfeeder frame on bearings. Bearings should be self-aligning to ensure bending stresses do not prematurely fatigue the welds on the pulley face. Self-aligning bearings also allow for easier mounting and alignment with all the interconnections of the rotating parts. Flange or pillow block style are normally used, however split housing style can also be applied that allows for shaft removal while maintaining bearing position

Figure 2.9 Bearings

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j. Motor The motor for the weighfeeder must meet or exceed the power requirement for the application. Inverter duty motors are normally required to achieve the weighfeeder turn down ratio or rate range. Inverter duty motors feature a constant torque output. Constant torque is a term used to define a load characteristic where the amount of torque required to drive the machine is constant regardless of the speed at which it is driven. For example, the torque requirement of most conveyors is constant. The turn down ratio is determined by taking the max flow rate and dividing it by the min flow rate. Weighfeeder applications will typically have a 10:1 turn down ratio, and the unit must provide accurate weighing results in this range. A standard AC motor is only rated for a 6:1 turn down ratio. Special force air cooling with a separate line feed or over sizing the motor can accomplish this however some motors have standard inverter duty ratings up to 1000:1. With an inverter duty motor and a VFD in the PID loop with the weighing integrator, the belt speed can achieve the required turn down ratio.

Figure 2.10 Motor

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k. Gear Reducer The motor for the weighfeeder is running at a very high speed, 15001800 RPM, so a gear reducer converts that speed to a suitable belt travel speed for accurate weighing and conveying. The gear reducer sizing is dependent on many application details such as belt width, material profile, conveyor length, material bulk density, and infeed length, as well as motor power, shaft size, bearing size, and environmental conditions. The torque required by the application must be met with a minimum of a 1.2 safety factor. This allows for some jamming to occur without damaging the gear reducer. A hollow bore shaft mount style is the most popular option as it can be easily replaced and maintained compared to a belt or chain drive style system. The helical bevel style gear reducer provides optimum torque ratings as well as compact mounting and versatile installation options. The input of the gear reducer must match the flange type of the motor. The orientation of mounting has an impact on the quantity of oil that is to be used. The application will provide a precise reduction ratio required; the next highest value provided by the gear reducer manufacturer is sufficient for selection. Gear reducer construction is limited, however in wash down applications they can be food grade epoxy coated. Food grade oil can also be supplied when required.

Figure 2.11 Gear Reducer

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l. Belt Tensioner The belt tension must remain constant during operation. For critical or high accuracy applications, a gravity actuated belt tensioner allows for changes in tension due to temperature influences or material flow changes. The driven pulley bearings are normally mounted on some kind of telescoper or threaded bearing slider to properly track and tighten the belt.

Figure 2.12 Belt Tensioner

m. Belt Scraper Keeping the belt clean during operation is critical for weighing applications as material can build up and continuously be weighed without discharging into the process, creating a performance offset. The belt scraper cleans the material contact side of the belt at the discharge end. The scraper blade should be positioned so that material that is cleaned off the belt enters into the process. The scraper blade can contact the belt from tension of a spring or counterweight. The blade length needs to provide adequate cleaning, while also allowing for minor belt tracking movements and not colliding with belt flanges.

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Figure 2.13 Belt Scraper

n. Load Cell Load cell is an electrical device test device that can convert an energy into another energy commonly used to convert a force into an electrical signal. The change from one system to another is not straightforward in two stages but must go through the mechanical regulatory stages, the power and energy can feel the change of condition from good to unfavorable. In strain gauge (load cell) or commonly called strain gauge deformation. Strain gauge measures changes that affect strains as electrical signals, because effective changes occur in electric wire resistance loads. A load cell / slot typically consists of four aspects of the strain gauge in the configuration system at Wheatstone Bridge. Cell / load slot of a strain gauge or two strain gauges. Electrical signal output is usually supplied and sequenced several millivolts and requires amplification by the instrumentation amplifier before it can be used. The output from monitoring of changing conditions can be increased to calculate the force applied for the observation and monitoring of the condition . The following is a picture of the strain gauge and Wheatstone Bridge.

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Figure 2.14 Strain Gauge

Figure 2.15 Wheatstone Bridge

Strain gauge is the most important part of a load cell, with a function to detect the magnitude of the distance dimension changes caused by a force element. Strain gauge is commonly used in precision measurement of force, weight, pressure, torque, displacement and other mechanical quantities. Afterwards it is converted into voltage energy into mechanical members. The gage strain results in a change in the value of resistance proportional to the long-term changes or changes through the length of the process.

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Figure 2.16 Load cell on Weighfeeder

2.1.5. Parameter Operasi CCR Interface    

Feed Rate Q ( Tonnage ) Dolomite ratio Power Consumption

kg/s t/h % kW

Calibration Interface 

Belt Load

kg/m



Belt Speed

m/s



Qr

%

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2.2 Spesification of Dolomite in Nusakambangan Quarry 2.2.1

Main Utility

In the manufacture of portland cement, dolomite is one of the additive materials with to reduce clinker factor. Dolomite is very important for cement making process because in dolomite there is a chemical composition which becomes an important criterion in the proportion of raw materials of cement production such as CaO, MgO and other elements. In PT Holcim Indonesian Tbk Cilacap dolomite mining factory is conducted in Nusakambangan Island.

2.2.2

Characteristic of Material

Is an anhydrous carbonate mineral formed from calcium magnesium carbonate, ideally CaMg (CO3) 2. The term is also used for a sedimentary rock of carbonates which is predominantly formed from dolomite minerals. This limestone rock contains many micro nutrients: SiO2; Al2O3; Fe2O3, as well as macro nutrients MgO and CaO. Benefit of Dolomite 1. Buildings Materials Dolomites of a soft or crushed size can be used as a base material for road construction, concrete aggregates, and asphalt.

2. As cement making material Dolomite can also be utilized as one of the basic ingredients of cement making, namely cement clinker mortar, its manufacture is by adding about 40% dolomite to the cement. This can help speed up the hydration of cement.

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CHAPTER III METHODOLOGY 3.1 Flow Chart Below is a flow chart chart of the Case Study implementation method:

START

Find Problem

Literratur & Field Studies

Analysis & Problem Solving Decline

Report

Approved

FINISH

Figure 3.1 Flow Chart Diagram of Methodology

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Beginning Started a case study with guidance from field employees and lecturers from PNJ.

3.2 Find Problem The method of choosing a tool that will be analyzed for case study based on the many problems contained in the tool. Here we choose Weighfeeder to be our case study material, because there is one problem that often occur in the tool, namely Belt Slip.

Figure 3.2 Data time, amount, dan causes stop in Finish Mill Area

3.3 Literatur Study Learn the design and specifications of the Weighfeeder, and understand how the tool works to analyze the problems that occur in the tool. First: look for related data about the tools we will analyze by asking the field employees, and also can search the source of the manual book contained in the library.

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Second: process the data that has been obtained into a report and connect the data with each other to determine what the root of the problem is likely to cause the problem. Third: to discuss with the supervisor and supervisor to make a good report and in accordance with the issues that we will lift as the Case Study.

3.4 Analysis & Problem Solving After completion of the literature study, an analysis of quality aspects, security aspects, and analyzing the profitability will be obtained after our analysis is applied. The analysis is done by: First: look at the actual conditions in the field like what, and what problems are there in the area. Second: look at stop data and production data to see why the problem occurred and how to solve it in order to solve it. Third: survey to related employees on the tool, when problems occur what should be done in order to overcome temporarily, and ask when the problem occurs what kind of tool conditions, so it can take a conclusion to add to the root of the problem that may be the main cause Fourth: after all is fulfilled, the final stage determines the root cause of the problem that is causing the problem, and provides a solution to the problems that occur so that the problem does not recur in the future and does not add another problem.

3.5 Report After the literature study and problem analysis as well as problem solving, subsequent reports in the form of papers and presentations to display during the trial, and before being shown will be tested or examined by the supervisor whether feasible or not, if appropriate, will be approved and signed, if not feasible it will be revised.

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CHAPTER IV DISCUSSION

4.1 Weighfeeder 534-WF2 Weighfeeder (Belt Scale) is a tool that serves to weigh material and transport material in the cement industry. In PT Holcim Indonesia Tbk. The Cilacap Factory, Weighfeeder 534-WF2 serves to weigh and transport dolomite from Dolomite Bin to Belt Conveyor 534-BC4 and then to 564-BM2 Ball Mill. Material that is transported by weighfeeder is dolomite with 20% -35% of Ball Mill's total capacity of 250 ton / hour. Dolomite is used to reduce clinker factor, ie the amount of clinker used in the manufacture of cement. The use of dolomite also aims to reduce the selling price of cement without reducing the quality of the cement itself. The number of clinker used is as much as 65% -75% of the amount of Ball Mill capacity. The remaining gypsum and fly ash are added to the cement mix of 5% -10%.

4.2 Specification of Weighfeeder 534-WF2 This is table that show the specification of Weighfeeder 534-WF2 in Finish Mill Area at Holcim Plant. Item

General

Material Conveyed

Detail

Unit

Data

Type

-

DMO-36

Capacity( range )

t/h

30 MTPH

Accuracy

%

± 1/2

Width of feeder

mm

900

Shaft centers

mm

3708

Speed range

m/min

.10 M/S

Description

-

Dolomite Add.

Size

mm

≤ 30

23

Prefeeder

Spillage Conveyor

Motor

Temperature

ºC

Ambient

Moisture Content

%

10

Bulk Density

t/m³

Bin

Type

-

N/A

Installed power

kW

N/A

Type

-

N/A

Capacity

t/h

N/A

Size

Mm

N/A

Installed power

kW

N/A

Type

-

DC

Installed power

kW

1.12

Speed

rpm

1750

Tabel 2.1 Specification of Weighfeeder

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4.3 Location of Weighfeeder 534 – WF2

Figure 4.1 Location of Weighfeeder

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Weighfeeder (Belt Scale) is a tool that serves to weigh material and transport material in the cement industry. In PT Holcim Indonesia Tbk. Cilacap Factory, Weighfeeder 534-WF2 functions to weigh and transport dolomite from Dolomite Bin to Belt Conveyor 534-BC4 and then to Ball 564-BM2.

4.4 Performance Analysis of Weighfeeder 534-WF2 ( 2017 )

Figure 4.2 Data number of stop in Finish Mill Area

During 2017, the amount of stop due to Breakdown Unschedule in Finish Mill area line 2 is dominated 66 times. Where Weighfeeder 534-WF2 ranks third with a number of stop Breakdown Unschedule is 7 times.

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Figure 4.3 Data stop duration Finish Mill area

During 2017, the amount of stop duration due to Breakdown Unschedule in Finish Mill area line 2 is dominated by mechanical trouble which reached 297 hours. Where Weighfeeder 534-WF2 ranks third with a duration of hours Breakdown Unschedule of 46 hours.

PROBLEM IN WEIGHFEEDER 534-WF2 (2017) Belt Slip

Material Plug

43% 57%

Figure 4.4 Problem in Weighfeeder

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During 2017, the most problem that happened in Weighfeeder 534-WF2 Finish Mill area line 2 is dominated by belt slip that have 57%. Meanwhile material plug problem is 43%. 4.5 Belt Slip

Figure 4.5 Belt Slip Schema

Belt slip is when the friction grip becomes inadequate. When head pulley turn, it doesn’t tight belt properly so belt not running and tail pulley not turn. This may cause some forward motion of the driver without carrying a pulley driven with it. This is called the slip of the belt and is generally expressed as a percentage. Difference between slip and creep in drive belt Slipping Slip caused by wrong tension on the belt so that the moving pulley moves and the movable pulley is not moving Creep Belt is made of low modulus material. Thus there will be a significant change in the length of the belt in moving from the tight side voltage to the sagging side stress and hence creep occurs. This can also happen because the pulleys do not parallel with each other. This is more prominent in flat belt propulsion. To avoid creep, the pulley is crowned in the middle so there is no relative movement between the pulley and the belt. Both slip and creep cause a relative movement between the pulley and the belt. It also reduces power transmission. This should be reduced to a minimum.

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4.6 Belt Slip in Weighfeeder 534-WF2 In this case study we chose the weighfeeder tool to be our analysis and research material, and after observation in the field there are some problems that often occur in the tool such as overload material, belt slip, blocking material, etc. For this case we specifically analyze one problem that is not easy to detect either from CCR or patrol and this problem is quite often so it can harm the factory because if dolomite is not channeled then the use of clinker will be high and with the selling price set in the market of course the factory will suffered a loss in production terms, also incurred other costs for equipment repairs. In the case of Belt Slip itself, several causes of the problem have been identified. From the cause it is hoped to find the source of the most potential problem for Belt Slip and can find the right solution to reduce or eliminate the problem. Cause Belt Slip among others as follows: 1. Worn Lagging head pulley 2. Belt Loose 3. Overload material in BC 4. Material too sticky 5. Error load cell ( dirty )

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4.7 Root Cause Analysis of Belt Slip in Weighfeeder 534-WF2

Fault Adjust Belt tension

Caused of vibration of machine

Belt Slack Long Been Used

Belt Slip

Head and Tail Pulley not tight belt properly

Overload Material fall

Worn lagging head Surface of head and tail pulley contaminated by material

Cleaner not work optimally

Coating material

Material too sticky

Figure 4.6 Root Cause Analysis

Based on the RCA table above the belt slip occurs due to two factors: belt slack and pulley do not bind belt optimally. 4.7.1 Belt Slack

Figure 4.7 Belt Slack Schema

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If the belt is slack then the belt does not bind perfectly to the pulley so that when the pulley spins the belt does not come spinning, belt slack itself can be caused by belt is worn, wear itself due to life time. A surprisingly small reduction in belt tension yields a proportionally large reduction in slack-side tension. Slip rates wildly increase as the slack-side tension approaches zero.

Belt Tension Adjuster

Figure 4.8 Belt tension adjuster

When the loose belt should be solved this problem by adjusting the firmness of the belt itself so that when the arrangement is done incorrectly then the belt will remain loose so that the belt slip will occur.

Figure 4.9 Belt tension

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Belt tension may be tested by pressing against the top of the belt midway between the two pulleys. The proper deflection is determined by the distance between the centers of the two shafts. To determine proper deflection simply multiply the distance between the center points of the two shafts.

Bar damper on chut outlet bin to 534-WF2 weighfeeder serves as a retarder impact material that falls from the bin so that the belt is not easily damaged. The addition of an excessive amount of bar dampers can also cause coating and Figure 4.10 Bar damper chute eventually blocking 4.7.2 Head and Tail Pulley not tight belt properly While for the pulley itself will not bind the belt properly because of several factors such as the lack of type of pulley to the application in the field, for example when the pulley is usually applied to the wet material then the pulley does not bind well. Another thing can be caused because the surface of the pulley is worn out so it can not run belt properly. The use of water in the dolomite bin may also cause water-borne pulleys resulting in belt slippage due to reduced standard friction.

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Tail Pulley does not wear rubber lagging. But on the surface of the tail pulley there is a groove.

Figure 4.11 Tail Pulley Weighfeeder

In Head Pulley there is a rubber lagging that prevents the wear pulley and increase the pull of the pulley against the belt.

Figure 4.12 Rubber Lagging Head Pulley

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Figure 4.13 Material Sticky

Sticky dolomite material is transported through a weighfeeder. Due to the sticky nature of the material sometimes this can cause blocking of the chute outlet bin so that water is used to smooth the flow of material but this may cause the pulley to be contaminated by the water resulting in reduced friction and resulting belt slippage.

Friction on the pulley and belt will be reduced because it is blocked by sticky material so that the pull is not maximal and will result in belt slip

Figure 4.14 Head pulley Weighfeeder

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The Number of Repair in Weighfeeder 534 - WF2 8 7 6 5 4 3 2 1 0

7

The Number of Repair 4

Belt

Roller Carier

1

1

Rubber Lagging

Bar Damper

Figure 4.15 Number of repair diagram in 2017

Thats figure its describe about the number of repair in weighfeeder 534WF2. Based on the figure the most part that have been repaired is belt in weighfeeder that have been repaired 7 times in 2017. The second is carrier roller as much 4 times in 2017. For rubber lagging and bar damper just have to repaired just 1 times. The Diagram show that Belt is the most part that damage in 2017 it can means that belt slip is caused by worn belt. And in 2017 also do replace rubber lagging once. It happens because the lifetime of rubber lagging is exhausted.

4.8 Maintenance Cost Analysis Caused by Belt Slip Cost analysis aims to analyze the impact caused by belt slip that occur and cause loss-cost costs for production, operations, and maintenance.

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Data Maintenance Cost di 534-WF2 tahun 2017/2018 Description 534-WF2 Repl Carrier Roller 534-WF2 Replace Blade Primary Cleaner 534-WF2 Rep Belt CC.534-WF2, Repair samb Belt nglupas CC.534-WF2 Replace Roller carier CC.534-WF2 Repl Belt ngelupas CC.534-WF2 Install Rubber lagging Bearing-Upgrade Shaft HeadPulley 534WF2 Rep Belt sobek sambungan Upgrade Shaft Head Pulley 534-WF2 534-CH4 Repl Bar damper chute dol 534-WF2 Rep Belt sobek 500 mm CC.534-WF2* Repl Carier roller bearing CC.534-WF2 Lagging Head Pully lUpgrade 534-WF2 Repl Carier roller under chute CC.534-WF2*Rep Belt WF Dolomit TOTAL

Total Planned Costs 2.767.470

Total Actual Costs 2.794.194

4.317.486 1.221.486 1.495.694 6.374.766 23.501.438 2.971.308

4.317.486 1.221.486 2.670.450 6.463.846 25.308.112 4.146.064

2.671.486 1.221.486 14.877.800 7.721.486 8.275.038

2.671.486 1.221.486 14.877.800 5.816.436 1.221.486

2.767.470

2.794.194

3.245.516 4.828.782 1.495.694 89.754.406

5.595.028 4.891.138 2.670.450 88.681.142

Tabel 4.1 Cost maintenance

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Data Operational Cost di 534-WF2 tahun 2017/2018 Operational 534-WF2 Replace Blade Primary Cleaner 534-WF2 Repl Carrier Roller 534-WF2 Rep Belt CC.534-WF2, Repair samb Belt nglupas CC.534-WF2 Replace Roller carier CC.534-WF2 Repl Belt ngelupas Bearing-Upgrade Shaft HeadPulley 534-WF2 CC.534-WF2 Install Rubber lagging 534-WF2 , Tie in WF Dolomit jalur 2 534-WF2 , Tie in WF Dolomit jalur 2 Rep Belt sobek sambungan 534-CH4 Repl Bar damper chute dol 534-WF2 Rep Belt sobek 500 mm CC.534-WF2* Repl Carier roller bearing 534-WF2 Repl Carier roller under chute CC.534-WF2 Lagging Head Pully lUpgrade CC.534-WF2*Rep Belt WF Dolomit 534-WF2 Check & Rep Joint belt TOTAL

Actual work 7,000 7,000 7,000 7,000 7,000 7,000 7,000 7,000 14,000 14,000 7,000 7,000 7,000 7,000 7,000 7,000 7,000 7,000 140,000

Cost Hour 1.221.486 1.221.486 1.221.486 1.221.486 1.221.486 1.221.486 1.221.486 1.221.486 2.442.972 2.442.972 1.221.486 1.221.486 1.221.486 1.221.486 1.221.486 1.221.486 1.221.486 1.221.486 24.429.720

Tabel 4.2 Cost operational

The table above is a table of costs incurred for repairs on Weighfeeder 534WF2 equipment related to belt slip for the year 2017-2018 or a year. From the above table it is known that the total cost planned to perform the activity is Rp 89.754.406,00. And the work that has been actualized until now requires a fee of Rp 88.681.142,00 and maintenance operational costs incurred by Rp 24,429,720.00. So total cost maintenance that incured is : Rp 88.681.142,00 + Rp 24,429,720.00 = Rp. 113.110.862,00

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4.9 Production Loss Analysis Caused by Belt Slip The loss of its own production due to stop equipment weighfeeder 534-WF2. Tonnage

: 210 ton/h

Duration Stop

: 37 hours

Cement Cost

: Rp 85.959,00 /ton

Loss = Tonnage x Duration Stop x Cement Cost = Rp 667.901.430,00 So the production loss in Cement when Weighfeeder 534-WF2 stop is Rp 667.901.430,00. The Effect of Weighfeeder Stop to Quality Cement that make loss production: Initial Cement Composition : Dolomit

27%

Gypsum & Fly Ash Bottom Ash

6%

Clinker

67%

Loss that caused by weighfeeder stop during 0-2 hours that will increase the quality of cement quality by increasing clinker factor. Cement composition when weighfeeder stop: Gypsum & Fly Ash Bottom Ash

6%

Clinker

94%

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CHAPTER V CONCLUSION 5.1 Conclusion In 2017 the Weighfeeder 534-WF2 equipment has a stop with a duration of 46 hours which is the third largest in the finish mill area where the cause is a belt slip. In 2017 maintenace cost at Weighfeeder 534-WF2 is Rp. 113.110.862,00. And the production loss is Rp. 170.829.280,00. Belt slip problems usually occur due to several factors such as lagging head pulley wear, belt loose, too much material on BC, material too wet, load cell error (dirty). And at Weighfeeder 534-WF2 belt slip occurs due to worn lagging pulley factor, worn belt and wet material.

5.2 Solution 1. Replace belt and rubber lagging pulley that has worn out. 2. Regularly ordering belt tension so that belt slip does not occur. 3. Cleaning the material that stick on the pulley because it can reduce friction between the belt and the pulley so it is not binding. 4. Upgrade rubber lagging into ceramic lagging.

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BIBLIOGRAPHY

[1] Technical Data of 534-WF2, Manual Book Weighfeeder Schenck

[2] Manual Book 101 Weighfeeder Schenck

[3] https://w3.siemens.com/mcms/sensorsystems/SiteCollectionDocuments/wt /application_guides/Weighfeeder_Application_Guidelines.pdf

[4] ABB. (2018, 2015). Technical Information System. Diambil kembali dari Knowledge Manager: http://hc-cc-tis-srv/km/