session six inventory fundamentals. 6-1a course outline session 1: introduction to supply chain...
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Session SixSession SixInventory FundamentalsInventory Fundamentals
6-1a
Course OutlineSession 1: Introduction to Supply Chain
Management.Session 2: Forecasting.Session 3: Master Planning.Session 4: Material Requirements Planning.Session 5: Capacity Management & Production
Activity Control.Session 6: Inventory Fundamentals.Session 7: Inventory Management.Session 8: Physical Distribution.Session 9: Quality Management and Purchasing.Session 10: Just-in-Time Manufacturing.
Objectives of Session
Present to participants the fundamentals of inventory including the classification of inventory, objectives and functions of inventory management, costs of inventory, classification and control of various inventory items and simple financial statements
6-2a
Session 6 Outcomes
After completing this session participants should be able to: State the importance of good inventory management.
Classify inventory based on flow of material Describe the functions inventories perform. Discuss the objectives of inventory management
6-2b
Session 6 Outcomes (cont.)
Define all the costs that are relevant to
inventory decisions. Read and develop simple financial statements Define and interpret simple inventory turns
ratio Conduct ABC analysis and suggest inventory
control for each class.
6-3
What is Inventory
Those stocks or items used to: support production (raw materials
and work- in-process items), supporting activities (maintenance,
repair and operating supplies), and customer service (finished goods
and spare parts)- APICS Dictionary
6-4
Aggregate Inventory Management• Deals with managing according to
its classification as: raw materials, work in process, and finished goods inventory as groups
Finance orientedInvolves
Flow and kind of inventory neededSupply and demand patternsFunctions inventory performObjectives of inventory managementCosts associated with inventory
6-5
Item Inventory Management
Management must establish decision rules about
individual inventory items:Importance of inventory itemsHow they are to be controlledHow much to order at one timeWhen to place an order
6-6a
Inventory and the Flow of Materials
Supplierraw
material
Supplier SupplierCompone
nts MRO
Work in processFinished
goodsWarehous
eWarehous
eWarehous
eCustomerCustomerCustomer
6-6b
Inventory Types
Inventory can be classified into the following:
Raw materialWork in processFinished goodsDistributionMaintenance, repair, & operating supplies
(MRO)
6-7a
Reasons for Carrying Inventory
The only good reason for carrying inventory beyond current needs is if it costs less to carry it than not.
Inventory allows the company to operate with different production rates and batch sizes throughout the supply production, and distribution systems.
6-7b
Reasons for Carrying Inventory
Decouples
Demand from supplyCustomer demands from finished
goodsFinished goods from
component availability
Output of one operation from output of preceding operation
Materials to begin from suppliers of production materials
6-8
Functions of Inventory
Anticipation:anticipate future demandFluctuation: cover fluctuation in supply or
demand (safety stock)Lot size: purchase more than neededTransportation: cover material movement
timeHedge: protect against price
fluctuation
6-9
Inventory Objectives
Best customer serviceLow-cost plant operationMinimum inventory investment
6-10
Basic Problem
Balance cost of carrying inventory with costs of not carrying inventoryCustomer serviceChanging production levelsPlacing orders
Sum of the cost of carrying inventory and the cost of not carrying inventory should be as low as possible
6-11
Inventory Costs
Item costsCarrying costsOrdering costsStock-out costsCapacity-related costs
6-12
Item costs
Cost of item and all costs to get item into the plant
ProductTransportationCustoms dutiesInsuranceDirect material, direct labor, and
factory overhead
6-13
Carrying Costs
Carrying costs can be broken down into three categories:Capital costs Money tied up in inventoryStorage costsSpace, personnel, and
equipmentRisk costs Obsolescence, damage,
pilferage, insurance, and deterioration
These costs increase with the amount of inventory carried
6-14a
Problem 6.1
Given the following percentage costs of carrying inventory, calculate the annual cost if the average inventory is $1,000,000. capital costs are 6%, storage costs are 9% of the average inventory value, and risk costs are 10%.
6-14b
Problem 6.1
Total costs of carrying inventory= 6% + 9% + 10% = 25%
Annual carrying cost= 0.25 1,000,000 = $250,000
6-15
Ordering Costs
Costs of placing and order with the factory or
outside supplier
Costs includeProduction controlSetup and teardownLost capacityPurchase order
6-16a
Problem 6.2
Given the following data, calculate the average
cost of placing one order.
Annual production control cost = $200,000
Average cost of setup and teardown = $200Number of orders per year = 20,000
6-16b
Problem 6.2
Annual production control cost = $200,000
Average cost of setup and teardown = $200Number of orders per year =
20,000
Average cost of placing an order 200,000 20,000
= + 200 = $210
6-17
Stock-out costs
If demand during the lead time exceeds forecast
and available inventory, we can expect a stock-
out, causingBackorder costsLost sales costsLost customer costs
6-18
Capacity-Related Costs
Cost of changing production levelsOver-time/under-timeHiringLayoffTrainingShift premiums
Can be avoided by leveling production (but may build inventory)
6-19a
Problem 6.3Next year quarterly sales forecast is 2000, 3000, 4000, and 3000. Calculate a level production plan, quarterly ending inventory, and average quarterly inventory.
Assume average quarterly inventory is the average of the quarter’s starting inventory and ending inventory. Opening and ending inventories = zero.
If inventory carrying costs are $3 per unit per quarter, what is the annual cost of carrying inventory?
6-19b
Problem 6.3 (Solution)
Q1 Q2 Q3 Q4
Sale2,00
03,00
04,00
03,00
0Production
Ending inventoryAverage inventory
Inventory costAnnual inventory carrying cost
=
6-19c
Problem 6.3 (Solution)
Q1 Q2 Q3 Q4
Sale2,00
03,00
04,00
03,00
0
Production3,00
03,00
03,00
03,00
0Ending
inventory1,00
01,00
00 0
Average inventory
5001,00
0500 0
Inventory cost1,50
03,00
01,50
00
Annual inventory carrying cost = 1500 + 3,000 + 1,500 + 0 = $6,000
6-20
Accounting Systems
Accounting systems classify activities of a company into five types of accounts
balance sheet accounts
income statement accounts
Assets Liabilities Owner’s equity
RevenuesExpenses
6-21
Balance Sheet Equation
Assets = Liabilities + Owners’ equity
Assets: Anything of valueLiabilities: Amounts owedOwners’ equity: What is left over
after liabilities are paid
6-22a
Problem 6.4
A. If the owner’s equity is $1,000 and liabilities are $800, what are the assets worth?
Assets =
6-22+
Problem 6.4
A. If the owner’s equity is $1,000 and liabilities are $800, what are the assets worth?
Assets = Liabilities + Owner’s equity= 800 + 1,000= $1,800
6-22b
Problem 6.4
B. If the assets are $1,000 and liabilities are $600, what is the owners’ equity?
Owners’ equity =
6-22b+
Problem 6.4
B. If the assets are $1,000 and liabilities are $600, what is the owners’ equity?
Owners’ equity = Assets – liabilities= 1,000 – 600 = $400
6-23
Income Statement
Income = Revenue – Expenses
Revenue:Comes form the sale of goods and servicesIncreases owners’ equity
Expenses: Costs incurred in earning revenue
Decreases owners’ equityClassified as:- Cost of goods sold (labor, material,
OH)- General and administrative expense
6-24
Income StatementRevenue $1,000,000Cost of goods sold
Direct labor $200,000Direct material 400,000Overhead 200,000
Total cost of goods sold – 800,000Gross margin (gross profit) $ 200,000General and admin. expense – 100,000Net income (profit) $ 100,000
6-25a
Problem 6.5
A. Given the following data, calculate the gross margin and net income.
Revenue = $1,500,000Direct labor = $300,000Direct material = $500,000Overhead = $400,000General & admin expenses = $150,000
6-25b
Problem 6.5
Revenue $________Cost of goods sold
Direct labor $________Direct material $________Overhead $________
Total cost of goods sold $________Gross margin (gross profit) $________General & admin expense $________Net income (profit) $________
6-25b+
Problem 6.5Revenue $1,500,000Cost of goods sold
Direct labor $300,000Direct material $500,000Overhead $400,000
Total cost of goods sold $1,200,000
Gross margin (gross profit) $300,000General & admin expense $150,000Net income (profit) $150,000
6-25c
Problem 6.5
B. How much would profits increase if, through better materials management, material costs were reduced by $50,000?
If material costs were reduced by $50,000, income would increase by:
6-25c+
Problem 6.5
B. How much would profits increase if, through better materials management, material costs were reduced by $50,000?
If material costs were reduced by $50,000, income would increase by:
$50,000
6-26
Cash Flow Analysis
The inflow and outflow of cash in the business over a given period of time
To survive, a business must have the cash available to pay its bills
6-27
Cash Flow
Inventory state Effect on cash flow
Raw material Cash outflowWork in process Cash outflowFinished goods Cash outflowAccounts receivable paid Cash inflow
6-28
Inventory Turns
A measure of how effectively inventory is being
used
ExampleAnnual cost of goods sold =
$1,000,000Average inventory = $500,000
inventory average
sold goods ofcost annual turnsinventory
2000,500
000,000,1 turnsinventory
6-29a
Problem 6.6
If the annual cost of goods sold is $10 million
and the average inventory is $2.5 million:
a. What is the inventory turn ratio?b. What would be the reduction in average
inventory if, through better materials management, inventory turns were increased to 10 times per year?
c. If the cost of carrying inventory is 20% of the average inventory, what is the annual savings?
6-29b
Problem 6.6
a. Turns Ratio = =
b.
= $________________ Reduction in inventory =
=c. Annual savings =
$
$
ratio turns
goods ofcost annual inventory Average
6-29c
Problem 6.6
a. Turns Ratio = = 4
b.
= = $1,000,000 Reduction in inventory = 2,500,000 –
1,000,00 = $1,500,000c. Annual savings = 20% 1,500,000 =
$300,000
ratio turns
goods ofcost annual inventory Average
000,500,2$0$10,000,00
100$10,000,00
6-30
Strategic Performance Measures
Strategic performance measures relate to a company’s long-range goals
Measures includeProfitabilityMarket shareGrowthProductivity
6-31
Problem 6.7
Given the following information, calculate the
annual cost of carrying inventory.
Orders placed per year = 1,000Receiving cost per order = $15Annual office expense = $8,000Average inventory = $500,000Cost of capital = 10% of average inventory valueCost of storage = 8% of average
inventory value
6-32a
Problem 6.7Orders placed per year = 1,000Receiving cost per order = $15Annual office expense = $8,000Average inventory = $500,000Cost of capital = 10% of ave.
inventoryCost of storage = 8% of ave.
inventory
Annual cost of carrying inventory=
6-32b
Problem 6.7Orders placed per year = 1,000Receiving cost per order = $15Annual office expense = $8,000Average inventory = $500,000Cost of capital = 10% of ave. inventoryCost of storage = 8% of ave. inventory
Annual cost of carrying inventory= Ave. inventory×(cost of capital + cost of storage)= 500,000 × (0.10 + 0.08) = $90,000
6-33a
Problem 6.8An importer operates a small warehouse that has the following annual costs. Wages for purchasing are $80,000, purchasing expenses are $70,000, and customs brokerage is $45 per order. The estimated cost of financing the inventory is 10%, storage costs are 7%, and risk costs are 10%. The average inventory is $500,000, and 10,000 orders are placed in a year. What are the annual ordering and carrying costs? What is the average ordering cost?
6-33b
Problem 6.8
Annual ordering cost =
Annual carrying cost =
Total annual cost =
Average ordering cost =
6-33c
Problem 6.8
Annual ordering cost = 80,000 + 70,000 + (45 10,000) = $600,000
Annual carrying cost = 0.27 500,000 = $135,000
Total annual cost = 600,000 + 135,000 = $735,000
Average ordering cost = 600,000 10,000 = $60
6-34a
Problem 6.9
Given the following data, calculate the gross margin and net income.Revenue = $2,000,000Direct labor = $200,000Direct material = $800,000Overhead = $600,000General & admin expenses = $200,000
6-34b
Problem 6.9
Revenue $________Cost of goods sold
Direct labor $________Direct material $________Overhead $________
Total cost of goods sold $________Gross margin (gross profit) $________General & admin expense $________Net income (profit) $________
6-34c
Problem 6.9
Revenue $2,000,000Cost of goods sold
Direct labor $200,000Direct material $800,000Overhead $600,000
Total cost of goods sold $1,600,000Gross margin (gross profit) $ 400,000General & admin expense $ 200,000Net income (profit) $ 200,000
6-35a
Problem 6.10
If the annual cost of goods sold is $48 million
and the average inventory is $12 million:a. What is the inventory turns ratio?b. What would be the reduction in average
inventory if, through better materials management, the turns ratio were increased to six times per year?
c. If the cost of carrying inventory is 25% of the average inventory, what is the annual savings?
6-35b
Problem 6.10
a. Turns Ratio =
b. Average inventory =
Reduction in inventory =
c. Annual savings =
6-35c
Problem 6.10
a. Turns Ratio = = 4
b.
= = $8,000,000 Reduction in inventory = 12,000,000 –
8,000,00 = $4,000,000
c. Annual savings = 25% 4,000,000 = $1,000,000
ratio turns
goods ofcost annual inventory Average
000,000,12$0$48,000,00
60$48,000,00
6-36a
ABC Inventory Control
For basic questions must be answered:
What is the importance of the inventory items?
How are they to be controlled?How much should be ordered at one
time?When should an order be placed?
6-36b
Concept of ABC Inventory Control
A small number of items will present the most critical values.
ABC inventory control separates the most significant items from the less important.
It is used to determine the degree and level of control used.
6-37
ABC Classification
A items20% of the items account for 80% of the total dollar usage
B items30% of the items account for 15% of the total dollar usage
C items50% of the items account for 5% of the total dollar usage
6-38
ABC Process
1. Establish the item characteristics that influence the results of inventory management
Annual dollar usageScarcity of materialQuality problems
6-39
ABC Process
2. Classify items into groups based on the criteria established
3. Apply a degree of control in proportion to the importance of the group
6-40
Example of ABC AnalysisPart number
Annual unit usage
Unit cost ($)
Annual usage ($)
1 1,100 2 2,2002 600 40 24,0003 100 4 4004 1,300 1 1,3005 100 60 6,0006 10 25 2507 100 2 2008 1,500 2 3,0009 200 2 40010 500 1 500
Total $38,250
6-41a
Example ABC Analysis-cont.Part
numberAnnual $
usageCumulat
ive $ usage
Cumulative % $ usage
Cumulative % of items
2 24,000 24,000 63 105 6,000 30,000 78 208 3,000 33,000 86 301 2,200 35,200 92 404 1,300 36,500 95 5010 500 37,000 97 603 400 37,400 98 709 400 37,800 99 806 250 38,050 99 907 200 38,250 100 100
6-41b
Example ABC Analysis-cont.Part
numberAnnual $
usageCumulat
ive $ usage
Cumulative % $ usage
Cumulative % of items
2 24,000 24,000 63 105 6,000 30,000 78 208 3,000 33,000 86 301 2,200 35,200 92 404 1,300 36,500 95 5010 500 37,000 97 603 400 37,400 98 709 400 37,800 99 806 250 38,050 99 907 200 38,250 100 100
6-41c
Example ABC Analysis-cont.Pareto (ABC) Chart
0
20
40
60
80
100
0 20 40 60 80 100
% no. of items
% a
nn
ual
usa
ge
A B C
6-42a
Problem 6.11
Analyze the given data to produce an ABC classification based on annual dollar usage.
Item no.
Annual $ usage
1 13,1892 156,1273 3344 8,4935 42,7496 5,5897 19,5628 241,8739 1,96210 10,112
Total 500,000
6-42b
Problem 6.11Item
no.
Annual $ usage
Cum. $ usage
Cum. % $ usage
Cum. % of items
Item Clas
s
6-42b+
Problem 6.11Item
no.
Annual $ usage
Cum. $ usage
Cum. % $ usage
Cum. % of items
Item Clas
s
8 241,873
241,873 48.37 10 A
2 156,127
398,000 79.60 20 A
5 42,749 440,749 88.15 30 B
7 19,562 460,311 92.06 40 B
1 13,189 473,500 94.70 50 B
10 10,112 483,612 96.72 60 C
4 8,493 492,105 98.42 70 C
6 5,589 497,694 99.54 80 C
9 1,962 499,656 99.93 90 C
3 344 500,000 100.00 100 C
Total
$500,000
6-42c
Problem 6.11Pareto (ABC) Chart
0
20
40
60
80
100
0 20 40 60 80 100
% no. of items
% a
nn
ual
usa
ge
A B C
6-43
Control Based on ABC ClassificationTwo general rules to followHave plenty of low-value itemsUse control effort saved to reduce
the inventory of A items
A items: Tight controlB items: Normal controlC items: Simplest possible control
6-44
Inventory Control of A Items
A items: Tight control
Complete, accurate recordsRegular, frequent review by
managementFrequent review of forecastsClose follow-up
6-45
Inventory Control of B Items
B items: Normal control
Good recordsNormal processing
6-46
Inventory Control of C Items
C items: Simple control
Make sure there are plentySimple or no recordsLarge order quantities
6-47a
Problem 6.12
Use the given data to classify into A, B, C groups based on annual dollar usage (demand).
ItemAnnua
l Dema
nd
Unit cost $
1 21,000 12 5,000 403 1,600 34 12,000 15 1,000 1006 50 507 800 28 10,000 39 4,000 110 5,000 1
6-47b
Problem 6.12Item no.
Annual Deman
dUnit
cost $Annual $ usage Rank Clas
s
1 21,000 12 5,000 403 1,600 34 12,000 15 1,000 1006 50 507 800 28 10,000 39 4,000 110 5,000 1
Total
6-47b+
Problem 6.12Item no.
Annual Deman
dUnit
cost $Annual $ usage Rank Clas
s
1 21,000 1 21,000 4 B2 5,000 40 200,00
0 1 A3 1,600 3 4,800 7 C4 12,000 1 12,000 5 B5 1,000 100 100,00
0 2 A6 50 50 2,500 9 C7 800 2 1,600 10 C8 10,000 3 30,000 3 B9 4,000 1 4,000 8 C10 5,000 1 5,000 6 C
Total
380,900
6-47c
Problem 6.12Item
no.
Annual $ usage
Cum. $ usage
Cum. % $ usage
Cum. % of items
Class
6-47c+
Problem 6.12Item
no.
Annual $ usage
Cum. $ usage
Cum. % $ usage
Cum. % of items
Class
2 200,000
200,000 52.5 10 A
5 100,000
300,000 78.8 20 A
8 30,000 330,000 86.6 30 B
1 21,000 351,000 92.2 40 B
4 12,000 363,000 95.3 50 B
10 5,000 368,000 96.6 60 C
3 4,800 372,800 97.9 70 C
9 4,000 376,800 98.9 80 C
6 2,500 379,300 99.6 90 C
7 1,600 380,900 100.0 100 C
380,900
6-47d
Problem 6.12
Pareto (ABC) Chart
0
20
40
60
80
100
0 20 40 60 80 100
% no. of items
% a
nn
ual
usa
ge
A B C
6-2a
Session 6 Outcomes
After completing this session participants should be able to: State the importance of good inventory management.
Classify of inventory based on flow of material Describe the functions inventories perform. Discuss the objectives of inventory management
6-2b
Session 6 Outcomes (cont.)
Define all the costs that are relevant to
inventory decisions. Read and develop simple financial statements Define and interpret simple inventory turns
ratio Conduct ABC analysis and suggest inventory
control for each class.