Question

A manufacturer of aluminium cabinets (built-in cabinets in vehicles) delivers 50 cabinets per day to a customer. The fluctuation is 25 pieces per week. The customer demand must be 100% fulfilled.
The processing time per cabinet is 20 minutes in machining (3-shift operation possible), 24 h for 55 cabinets in coating (incl. drying time) and 0.5 h in assembly incl. quality inspection. In assembly up to 4 workstations can work in parallel. After assembly there is a buffer of up to 25 cabinets. A buffer of one daily quantity should be available before each processing step. One cabinet per day is sorted out due to quality defects in assembly. There are no other quality problems.
There is space on a load carrier for the parts of up to 15 cabinets (without necessary C parts). The load carriers are loaded after machining and then serve as load carriers until assembly.
For your calculations, assume 20 working days / 4 weeks per month and an equally distributed working time of 40h/week.
a) How many Kanban are needed for the system?
b) What is the maximum stock in circulation?
c) How would you provide standard parts, e.g. screws and hinges (classified as CXK in the supply concept) in the assembly? Explain your decision.

Answer 1

Following points are noted from the write-up

1. Manufacturer deliver 50 cabinets per day

2. Weekly production fluctuation is 25 pieces per week thus weekly production quantity would be 50 x 5 days in week + fluctuation quantity = 250 + 25 = 275 pieces per week thus daily production quantity would be 55 numbers

3. Working Hr is 24 hrs (3 shift)

4. Processing work activity for production is as below,

a. Machining

b. Coating + Drying

c. Assembly + Quality inspection

d. Ready for delivery

“Kanban System” helps in evolving the overall production process and system. It focuses on four basic principles. This system was developed in 1940 in Japan to improve process efficiency.

a. Visualize work

b. Limit work in process

c. Focus on Flow

d. Continuous Improvement (Measure and Improve)

A - HOW MANY KANBAN ARE NEEDED IN SYSTEM

There would be Kanban Card for following process flow

1. Machining – Cutting, Bending, Shaping, Molding

2. Coating – 1^st Coat , 2^nd Coat

3. Drying

4. Assembly – Door, sections, locks and hinges

5. Quality Inspection

6. Ready for delivery

2. MAXIMUM STOCK IN CIRCULATION

i. Manufacturer deliver 50 cabinets per day

ii. Weekly production fluctuation is 25 pieces per week thus weekly production quantity would be 50 x 5 days in week + fluctuation quantity = 250 + 25 = 275 pieces per week thus daily production quantity would be 55 numbers

iii. Working Hr is 24 hrs (3 shift)

iv. There is space on a load carrier for the parts of up to 15 cabinets (without necessary C parts)

Based on above information, Maximum stock in circulation would be,

Demand Qty per day + fluctuation qty per day + buffer stock per day = 50 + 5 + 15 = 70 piece per day

Monthly quantity = 70 x 20 working day in month = 1400 Pieces of cabinet

3. Supply of standard parts

Based on the production capacity and stock in circulation 70 pieces x 20 day = 1400 Pieces in a month

Assuming 15 days lead time for spare parts i.e. after placing the order to delivery time is 15 days.

Based on above, 1 month inventory would be sufficient to cater to the monthly production of 1400 pieces. This would also help in keeping an optimum stock in the stores