In: Operations Management
Case - 3 | ||||||||||||||
You are newly appointed assistant plant manager and have been assigned the task of | ||||||||||||||
examining ordering policies for supplies used in production. You found that your employer | ||||||||||||||
was using an EOQ policy for ordering cases of lubricating oil. You called the finance | ||||||||||||||
department and was told that for the purposes of analysis, the appropriate holding cost | ||||||||||||||
was 24 % per year. Demand over the past three years was for 7486 cases or an average | ||||||||||||||
of 2495 cases per year. At a cost of $ 6.32 per case, the cost of ordering the oil was | ||||||||||||||
estimated to be $ 83 per order. You used these numbers to find the EOQ. | ||||||||||||||
EOQ = ? 2DS / H | .= ? [2* (7486 / 3) *83 ] / 0.24 * 6.32 | .? 523 | ||||||||||||
The result basically agreed with the employer's ordering size of 500. You then developed a table | ||||||||||||||
showing oil usage for the past 36 months. | ||||||||||||||
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Total | ||
Gross requirement 2003 | 345 | 28 | 417 | 52 | 0 | 379 | 288 | 76 | 221 | 34 | 322 | 227 | 2389 | |
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Total | ||
Gross requirement 2004 | 379 | 32 | 489 | 50 | 4 | 433 | 267 | 83 | 244 | 32 | 354 | 259 | 2626 | |
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Total | ||
Gross requirement 2005 | 368 | 4 | 423 | 48 | 15 | 382 | 306 | 84 | 218 | 38 | 333 | 252 | 2471 | |
Gross Total | 7486 | |||||||||||||
Note: | Holding cost is per period | |||||||||||||
Also the case assumes there are 36 periods | ||||||||||||||
So Holding cost is to be defined for a month | ||||||||||||||
Now you are going to experiment on the past figures to calculate optimal inventory cost. | ||||||||||||||
Q-1 Would lot for lot ordering be better than the current EOQ policy? Show calculations as proof. | ||||||||||||||
Q-2 Would part period balancing be the best possible policy? Show calculations as proof. | ||||||||||||||
Q-3 Is just in time inventory a relevant notion for lot sizing? | ||||||||||||||
Q-4 How many orders would you recommend in 36 months? Show order cost as proof. | ||||||||||||||
Q-5 Give recommendations with solid arguments? | ||||||||||||||
Q-6 Any suggestions for improvements. |
1. a. Based on EOQ of 523 units the total Cost of ordering + Inventory holding cost for 3 years is is 2429[ 810 + 877 + 742]
b. Based on Lot by Lot the cost is 996 * 3 = 2988
Hence the cost by EOQ method is lower that lot by lot
2.
1. EOQ =
Where D is Average annual demand
S is cost of ordering
H is annual holding cost per unit
= EOQ= 523
Below is the table where the Ordering Cost + Holding cost is calculated for Lot by Lot , EOQ and Part balancing method.
2. As shown above the total cost by part balancing is 1859 [ 740 + 603 + 516] its is lower than other methods.
3. Yes with lot size we order only the inventory required for the period and don't have any carry over inventory