Project Seminar

CONTENTS  CHECKWEIGHER  LOAD CELL

ACTIVITIES DONE STUDY OF CHECKWEIGHER DESIGN IMPROVEMENT COST REDUCTION SPACE UTILIZATION  CONCLUSIONS

CHECKWEIGHER DEFINITION  TYPES BASIC DEFINITIONS RELATED ASSEMBLY STAGES FACTORS AFFECTING ITS ACCURACY TECHNICAL SPECIFICATION APPLICATIONS COSTING OF CHECKWEIGHER BACK

DEFINTION A Checkweigher is a system that weighs items as they pass through a production line, classifies the items by preset weight zones, and ejects or sorts the items based on their classification. Main parts: Entry , scaling and exit platforms Stand, base plate Load cell Cabinet Rejection mechanism U bracket

CW 1200

TYPES OF CHECKWEIGHER Standard machines: • CW 600 • CW 1200 • CW 3000 Non-Standard machines: • CW 6000 • CW 10000

BASIC DEFINITIONS RELATED TO CHECKWEIGHER                

TARE WEIGHT TARGET WEIGHT PITCH NET WEIGHT REZERO SCALE LINEARITY STATIC WEIGHT DYNAMIC WEIGHT DYNAMIC WEIGHT COMPENSATION LOWER LIMIT UPPER LIMIT OPERATE DELAY OUTPUT HOLD DELAY SPEED PULSES /GRAM

BACK

LOAD CELL

Two main components  Flexures on a load bearing surface  Strain sensor Strain α displacement of sensors

Strain gauge under strain Wheatstone bridge RETURN

Rejection mechanisms

Air blast rejector

Push off rejector

Sweep type rejector

APPLICATIONS Over or underweight detection of product Check for open flaps on a carton or case Missing caps Bar code labels Metal contaminants Pharmaceuticals and medicines industry Foods industry BACK

ASSEMBLY STAGES OF CHECKWEIGHER STAGE

1 CABINET AND STAND ASSEMBLY

STAGE 2:- LEVELLING OF PLATFORM

STAGE 3:- ELECTRONIC CIRCUIT

STAGE 4:- ASSEMBLY

BACK

FACTORS AFFECTING CHECKWEIGHER ACCURACY Environment effects

The product

Vibrating Product

Loose Product

Improper Product Spacing

Unstable Vs. Stable Product

Variable Shaped Product

RETURN

Technical specifications Sr no

Parameter

Data

1

Overall system length

1100 mm

2

Belt Height from floor

700 mm + 100 mm

3

Direction of flow

Left to Right

4

Conveyor platform

5

Conveyor belt

350 mm Long - 200 mm Wide 200 mm

6

Weighing device

Load cell

7

Least count

0.1 gm

8

Reject mechanism

Air Blast

9

Display

Graphic LCD

10

Power requirement

220V / 1 ph/ 50 Hz / 2A

11

Pneumatic requirement

6 kg/cm2 BACK

Design improvement Sensor design modification

1] Clamp 1 2] Clamp 2 3] Angle for sensor mounting 4] Horizontal tube 5] Vertical tube

Angle for sensor mounting

Horizontal tube plate

Horizontal tube

Clamp 1

Clamp2

Sensor mounting design

Old design

Rejection bin modification

1] 2] 3] 4]

Top cover Bin Front cover Bottom cover

Top cover

Bin

Front cover

Bottom cover

Rejection bin

BACK

Cost saving Packing plate  Material change for height adjusting screw Quick cost saving calculation for

checkweigher

Packing plate Packing plate

Volume of plate = 115 x 162 x 2 = 37260 mm2 Cost=Rs 165

Monthly expenditure for 8 machines with 4

plates each

= 4 x 8 x 165 = Rs 5280 Cost of grinding base plate is = 0.25 x 162 x 115 = Rs 46.57 (Grinding cost = 25ps/cm2 ) Grinding instead of packing plate Machining cost for plates== 8 x 46.57 = Rs 372.6  Cost saving = 5280-372.6 = Rs 4907.4

Quick cost saving of checkweigher  A - checkweigher within a minutes  B - Line operating hours per day  C - Number of operating hours per /week  D - Average overfill per package in grams  E - Product cost per gram  F - Accuracy of checkweigher in grams at standard deviation of 2σ  G - Packages per year (G= A x 60 x B x C x 52 )  H - Current overfill cost per year(H=G x E x D )  I - Overfill cost with checkweigher(I= G x E x F )  J - Savings per year with a checkweigher(J=H-I )  K - Cost of checkweigher  K/J - Payback in years



 A =180 packages/min  B = 6 hrs/day  C=5 days/ week  D=10 gm  E=10/90

= Rs 0.0001/gm  F=0.2 gm  K= Rs 450000  G=18000000 packs /year  H=Rs 18000  I = Rs 360  J= Rs 17640  Payback= 25 months 

BACK

Height adjusting screw New Material: Delrin piece Old material: SS 202 and nylon Cost of old screw= Rs 400 Cost of piece = Rs60

for 4 machines = 4 x 340 = Rs 2560

Saving= 400- 60 = 340

SPACE UTILIZATION Proposed layout for stage 1

Existing layout Fish bone analysis for scrap storage Projected number of machines with proposed plan

Existing layout

Fish bone analysis

Scrap and machine floor space

Floor space occupied on putting two machines

PROJECTED NUMBER OF MACHINES

BACK

CONCLUSIONS Assembly of particular machine and effect of

constraints Concepts regarding checkweigher Attempt of cost estimation Design changes Plan for effective space utilization Payback of machine