Logistics And Supply Chain Management EXERCISE 1

Workshop

Stock

C1

C2

Cn

D = N(1000,500)

Per month

Product P is made in our workshop (other items are also made there).

The flux voltage ratio of P is 5% and the average machine engagement rate in the shop floor is 50%.

The adjustment time of the machines to manufacture a batch of P is 10 hours at 80 € / h.

The cost of the raw materials needed to make a product P is € 3.

The added value is € 3 per piece, excluding the cost of adjustment.

It takes a manufacturing cycle time T1 = 1 month to manufacture a batch of P.

The manufactured P products are stored before delivery.

The stock ownership rate is estimated at 20% per year.

The cumulative demand of the various customers constitutes a normal distribution of mean 1000 and standard deviation 500, per month. We accept a risk of stock shortage of 2.28%.

1) In your opinion, what is the type of this workshop and its mode of production management ?

2) Can Wilson’s formula be used to determine the optimal manufacturing lot size ? Why ?

3) What is the Co order cost here ? What is its numerical value ?

4) What does the unit price Pu correspond to here ? Calculate its value.

5) What is the optimum size Q1 * for the production batch of P?

6) What is the Ss1 safety stock used for ? What is its value ?

7) Draw the profile of the stock of P. What is the average period between 2 production orders ? What is the SC1 value of the manufacturing launch threshold ?

8) What is the cost price Pr1 of product P ?

9) P products are managed in kanban. Knowing that a container contains 10 P, how many kanbans must be put into circulation ?

A SMED action is initiated which makes it possible to reduce the adjustment time to 6 minutes. A rationalization of the flows in the workshop makes it possible to improve the RTF of P which goes from 5% to 15%.

NB : we will take Q1 * = 4000

10) What is the goal of this SMED action ?

11) Calculate the new optimal size Q2 * of the production batch of P ?

12) Draw the composition of the manufacturing cycle time T1 and the new cycle time T2. Identify the C1 and C2 chip times. Deduce the relation between T1 and T2.

13) What is the Ss2 value of the safety stock ?

14) Draw the new profile of the stock of P. What is the average period between 2 production orders ? What is the SC2 value of the manufacturing launch threshold ?

15) What is the cost price Pr2 of product P ?

16) If P products are managed in kanbans, how many kanbans must now be put into circulation ?

17) Conclusions on these improvements.

EXERCISE 2

Product P is manufactured in our workshop (we also manufacture other products there).

The manufactured P products are stored before delivery.

The cumulative demand of the various customers constitutes a normal distribution of mean 400 and standard deviation 100, per month. We accept a risk of stock shortage of 2.28%.

It takes Tp = 2 weeks (manufacturing cycle time) to complete a P Work Order (OFp). The launch of an OFp requires the equipment to be adjusted by an operator for 8 hours.

According to the range of P, there is 1 hour of VAT (Value Added Time) machine and labor to produce a product P.

The hourly cost of labor is 60 € / h and 30 € / h for machines.

To make 1P, you need 1A and 2B. These raw materials are purchased € 20 for 1A and € 10 for 1B, postage paid if the quantity ordered is greater than 100 units (postage paid means that there is no delivery charge, therefore no cost of delivery). order). The supplier replenishment deadline is 1 week.

To simplify, we suppose that the workshop operates 8h / day, 5 days / week, 4 weeks / month.

1) Can we use Wilson’s model to manage the stock of P ? Why ?

2) What is the Co production order cost here ? Calculate its value.

3) What does the unit price Pu correspond to here ? Calculate its value.

4) What is the optimal size Qp * of the production batch of P?

5) What safety stock Ss1 should be implemented to take into account the variation in customer demand ?

6) The workshop equipment sometimes breaks down 8 hours. What Ss2 safety stock should be implemented to take this new disturbance into account ?

7) What is the level of the security stock Ss to be implemented ?

8) Draw the profile of the stock of P. What is the average period between 2 production orders ? What is the SC value of the manufacturing launch threshold ?

9) What is the cost price Pr of product P when it leaves stock ?

10) Can we use Wilson’s model to manage the stocks of A and B ? If so, review the course and come back next year. If not, give 2 essential reasons for not using it and suggest a suitable model. On what dates and in what quantities should the purchase orders for A (OA A ) and B (OA B ) be issued ?

11) What is the RTF of a product P ?

12) Operators’ productivity is estimated at 75% (on an 8-hour working day, they do 6 hours of Value Added Work and 2 hours of breaks, meetings, social time, etc.). How many operators must be assigned to the production of P during the 2 weeks of the OFp ?