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Monday 27 May 2013

Material Selection

MATERIAL SELECTION
QUESTION 11.3
Which material property would you select as a guide in material selection if the chief performance characteristic of the component was:

PERFORMANCE CHARACTERISTIC
MATERIAL PROPERTY
a)
Strength in bending
Tensile strength
b)
Resistance to twisting
Hardness
c)
The ability of a sheet material to be stretched into a complex curvature
Ductility
d)
Ability to resist fracture from cracks at low temperatures
Malleability
e)
Ability to resist shattering if dropped on floor
Toughness
f)
Ability to resist alternating cycles of repeat heating and cooling
Thermal shock resistance


Friday 17 May 2013

Assignment Chapter 6


Q16.1)
From eq 16.19:
We get cost for size or capacity difference:
C1=Co (L1/L0) x=Co (1000/100)0.61
In 1985, for purchasing 10 new units, it will not cost 10 times more due to the economy scale but if purchasing for 22years later, the cost will increase due to the inflation.
Inflation per year = 5%
Original cost = $35,000
New original cost due to the inflation for 22 years later = 35,000 (1+0.05)22= $102,384
So, the estimate of the cost is:
C1 = 102,384 (1000/100)0.61 = $ 417,092
Q16.2)
Overseas subcontractor
Labor per shoe                                                            2.75
Materials                                                         9.00
Shipping and import duty                               3.50
Operating cost                                                 3.00
Profit                                                               1.75
U.S brand name shoe company
Purchase from subcontractor                          20.00
Research and development                             0.25
Promotion and advertising                              4.00
Sales, G&A                                                     5.00
Profit                                                               6.75    




Q16.3)
At break-even point, QB, cost using hard tooling = cost of using soft tooling.         
The chief cost elements are:
·         Cost of tooling, CH = $7500 and CS = $600
·         Cost of tool setup, SH= $60 and SC = $100. Parts made in batches, b, of 500 units.
·         Cost of making one part, CpH = $0.80 and CpS = $3.40
So, at break-even point
CH+ (QB/b) SH + CpH QB = CS + (QB/b) SS + CpS QB
QB = (CH-CS) / (((SS-SH)/b) + (CpS - CpH)) = (7500-600)/ ((100-60)/500) + (3.4-0.80))=6900/2.68 = 2574
At break-even point, hard tooling approaches become more effective than soft tooling. So, for 500 units, the best decision is to use hard tooling.

Q16.4
Prime cost
Direct labor                                                                 950,000
Direct material                                                                        2,150,000
Direct expenses                                                                       60,000
Direct engineering                                                       90,000
Direct engineering expenses                                       30,000
                                                                                    3,280,000                                (1)
Factory expense
Plant utilities                                                               70,000
Plant & equipment depreciation                                             120,000
Warehouse expense                                                     60,000
                                                                                    300,000                                   (2)
General and administrative expenses (G&A)            
Plant manager and staff                                                          180,000
Administrative salaries                                                            120,000
Office utilities                                                             10,000
                                                                                    310,000                                   (3)
Manufacturing cost = (1) + (2) +(3) = 3,890,000                   (4)
Sales expense = 100,000                                             (5)
Total cost = (4)+ (5) =3,990,000                                             (6)
Profit margin = profit / sales = P/S = 0.15
Sales (S) = Total cost (CT) + Profit (P)
S =CT + P = CT + 0.15S ;
S = CT / 0.85 = 3,990,000/0.85 = 4,694,118
The unit selling price of turbine is $4,694,116/60 units sold = $ 78,235

Material Selection


MATERIAL SELECTION
QUESTION 11.3
Which material property would you select as a guide in material selection if the chief performance characteristic of the component was:

PERFORMANCE CHARACTERISTIC
MATERIAL PROPERTY
a)
Strength in bending
Tensile strength
b)
Resistance to twisting
Hardness
c)
The ability of a sheet material to be stretched into a complex curvature
Ductility
d)
Ability to resist fracture from cracks at low temperatures
Malleability
e)
Ability to resist shattering if dropped on floor
Toughness
f)
Ability to resist alternating cycles of repeat heating and cooling
Thermal shock resistance