Datasheet

Thursday, 17 July 2003 MiniProject: Design Aspects Colin K McCord
EEE512J2 – Electronic Product Design Page 23 Chapter 4: Project Planning and Management
Ball Park Assessment Method: -
1. List all components/assemblies in the product.
2. Assess most expensive and least expensive items and determine probable cost order.
E.g. ECG Amplifier = 0.2, Batter pack and charger = 0.15, etc…
3. Rearrange components / assemblies in descending order of cost.
E.g. ECG Amplifier (0.2) most expensive, 9-way PCB D-type plug (0.003) least expensive
4. Apply Pareto rating, first general then detailed.
E.g. split items into three groups 60% (class A), 30% (class B) and 10% (class C) of total cost.
5. Estimate or otherwise determine the cost of one component / assembly.
E.g. ECG Amplifier estimated at £40.
6. Divide this cost by its Pareto rating for total component / assembly (product) ball park cost.
E.g. 40/.20 = £200
7. Add a generous contingency for Ball Park manufacturing cost.
E.g. Say 50% of gross cost: £210 + 50% = £315.
8. Determine Individual costs of component.
E.g. Microcontroller (PIC16F877) = 0.035*200= £7.00.
9. Determine the operative components of costs’ areas involved.
10. Assess components of cost.
11. Add final inspection, final assembly, final test etc.
12. Determine manufacturing cost including estimating contingency.
13. Add PISC + sales / admin + profit to get factory selling price.
E.g. Say 20%, hence factory selling price is £378.
14. Allow for retail mark-up (20-25%)
E.g. Say 20%, hence retail selling price is £453.60.
Note: This entire costing exercise is accomplished without any design work, this is a pre-emptive technique.
19 items were included in the costing sheet: -
• 4 items (21% of items) contributed to 60% of the total component cost.
• 5 items (26% of items) contributed to 30% of the total component cost.
• 10 items (52% of items) contributed to 10% of the total component cost.
4.4. Line Balancing
A balanced line is one where each work station is allocated a package of work which will take an equal
amount of time to complete as every other work station on the line. In practise this is difficult to achieve,
allow there are a couple standard manual methods (largest candidate rule, Kilbridge and Wester’s method,
ranked positional weights method) that managers can use to obtain a good solution (computational software
also exists). All methods provide a good solution approaching the true optimum and focus management
attention on problem areas.
Precedence constraints describe a situation where an operation must be carried out before another
operation can start. Positive zoning means that particular work element should be placed near to each other,
and negative zoning means that particular work elements should not be placed near to each other. Position
constraint (physical size) means that workers come to the product to perform their work. A precedence