Lean Manufacturing in AC vents manufacturing – Part 2

This is the part 2 of this series. Read Part 1 first

Observations are consolidated, reviewed and following actions are defined using different tools (Cause & Effect Diagram, IS / IS Not, Situation Mapping, differentiating between Value Added & Non Value Added operations & assembly specific requirements):

  1. Operations F G & H can be combined to 1 operation, hence reducing 2 operations.
  2. Operations K L & M can be combined to 1 operation, hence reducing 2 operations.
  3. Training to operator for in-process inspection in there respective cell. Self certified parts leave from the respective cell.
  4. List of value added operation & Non value added operations made.
  5. Many Inspection stages – Operation C / E / G / J /L /N are inspection stages – it is observed that independent inspection stages not required after every stage as they are non value added operations – build the concept of self certifying the parts. Hence reducing the stages from 6 to 2 (Only 2 critical stages are maintained, these are considered as Required Non value added operations), hence reducing 4 operations.
  6. Movement of operators & line stoppage can be avoided by adding an additional person to monitor the stock in the bins and refill as and when required as that in super market. This shall be maintained by implementation of KANBAN cards.
  7. Considering to Balance the process /operation time where a ever possible.

Considering all the above points’ modifications following activities are done:

  • Modification in assembly fixtures initiated to combine the operation.
  • Unwanted inspection stages are eliminated and modifications done in the existing 2 stages to ensure that all the product requirements are inspected.
  • Assembly cells re-structured and finally the Present layout mapping as below is achieved. (Following layout is achieved)

Work Cell - After Implementation of leanIMPROVED SITUATION OF AIR VENT ASSEMBLY LINE

Following are the cycle time for the improved process:

Leveled Production (Heijunka)
Observations after the process re-structuring:

  1. First piece from comes out after only 204 sec from the start of assembly line.
  2. Thereafter time required 68 sec / part.
  3. Person added to refill the bins – hence no stoppage of assembly for refilling of parts.
  4. Manpower used 8 operators + 1 person for refilling the parts = 9 nos
  5. Overtime not required.
  6. Unnecessary stages are eliminated.
  7. Stages / Cycle time is tried for balancing however there is a scope for lot of balancing.
  8. Some Inventory still exists at T-U / V-W operations.
  9. Supervisor is more confident to meet customer requirements.
  10. Maximum Non value added operations eliminated.
  11. In the existing situation 415 parts can be produced against the requirement of 400 / day.
  12. Space utilized is reduced to 7.2 x 2.2 meters.

Quantifiable Benefits are as follows:

  1. First and foremost benefit customer requirement can be meet in the normal working hours. Hence the sales increased from the normal shift working without any overtime.
  2. Increase in production quantity from 307 to 415, generating the spare capacity for 15 nos extra.
  3. Reduction of manpower from 15 to 9 nos. Hence the savings of 6 x 6000 = 36000 INR ($900) / month
  4. Overtime payment is nil i.e. the direct saving of $ 805 / month
  5. Overtime 2.2 hrs x 15 operators x 37.5 INR = 1237.5 / day
  6. 1237.5 INR x 26 working days = 32175 INR / month ($805)
  7. Hence the total direct savings per annum is $ 900 + $ 805 = $ 1705 / month x 12 months = $20460 p.a.
  8. Inventory level is reduced, however not eliminated.
  9. Spare space of 4.3 x 1.1 meters generated.
  10. This study has helped to learn more on improvement and to implement on other assembly line.

Lean Manufacturing in AC vents manufacturing – Part 1

As promised in lean for our organization contest, I am publishing one of the good quality articles sent by one of our readers in a series of two articles. You will be able to incorporate these learning in your lean manufacturing efforts. Thanks for Satish the author of this article.

Lean Implementation:

Brief Introduction: Hi , I am Satish N Ladwa from India, I am into supplier performance engineering in an Automotive company which is into the manufacturing of Instrument panel Assemblies(4 wheeler dash board) for OEM’s , department name itself indicates my main role , i.e. to improve the suppliers performance in terms of Quality , Cost & delivery.

Problem Definition:

Refer the below snap shot of the product, this is the Air vent sub- assembly (Air Vents are the outlet for the AC in the car) used in the Instrument Panel Assembly. Air Vent parts are plastic injection molded & assembled at supplier end. This assembly contains 21 individual parts.

Requirement of this assembly is 400 nos / day; however in the existing established assembly line only 305 to 310 parts can be assembled in the normal 8 hour working shift. Many a times this has resulted in stoppage of customer line.

Air Vent - Product Manufactured (Changed to avoid any copyright issues)
The Original Picture sent by the author was changed to any Copyright Issues

Waste Categories:
– 2.2 hrs of over time for 15 people + 1 Supervisor.
– 15 people needed to run the assembly line.
– Inventory observed at intermediate stages.
– Through put time more.
– Unable to meet customer requirements.

Causes: To understand the cause for the delays in supplies 2 days where spent on assembly line to study all operation and material flow. Considering the detail observation the existing situation is plotted (refer below layout) along with records of cycle time, resource requirements, space requirement etc.

Work place arrangement before lean manufacturingPROBLEMATIC SITUATION OF AIR VENT ASSEMBLY LINE

Following are the Cycle Time Details

 Cycle Time Variation And Non Leveled Production (Non Heijunka)

Observations are:

  1. First piece from comes out only after 361 sec from the start of assembly line.
  2. Thereafter time required 85sec / part.
  3. After every 100 nos operator found to leave there place to re-fill there bins with parts to continue with assembly, hence line stops for 10 mins
  4. After every ~2 hrs.
  5. Manpower used 15 nos.
  6. Overtime paid for ~2.2 hrs.
  7. Unnecessary stages are added hence consuming more time / manpower and space.
  8. Stages / Cycle time is not balanced.
  9. Inventory observed in-between A-B / E-F / J-K operations.
  10. Supervisor is always under pressure to meet customer requirements.
  11. In the existing situation only 307 parts can be produced against the requirement of 400 / day.
  12. Existing space utilized is 11.5 x 3.3 meters.

Read Part 2 Of this Post