Breakdown maintenance cost Optimum Cost of Maintenance
Spare parts Labor Down time (production loss) Overhead Consumables Hand tools, power tools and equipment Who will do maintenance? In-house Out-source
Decision to out-source Lack of expertise Too hazardous No experience Bound by contract Top management policy
Example The record of computer breakdown for Company PCK for the past 20 months is shown below. # of breakdown # of months breakdown occurs 0 1 2
3 4 8 6 2 Total 20 Each time computer breakdown estimated
loss is RM300 Contract preventive maintenance by company DK RM200 per month Should PCK contract out preventive maintenance to DK? Solution Step 1 Calculate expected number of breakdown (based on past records) if the company continue without service contract. Step 2
Compute expected breakdown cost per month with no preventive maintenance contract Step 3 Compute the cost of preventive maintenance Solution Step 4 Compare the two options and select the one which cost less Solution # of breakdown Frequency
0 1 2 3 4/20 = 0.2 8/20 = 0.4 6/20 = 0.3 2/20 = 0.1 Step 1 Expected # of breakdowns = (# of breakdown) x (frequency)
= (0)(0.2)+(1)(0.4)+(2)(0.3)+(3)(0.1) = 1.3 breakdown per month Solution Step 2 Expected breakdown cost = (expected # of breakdown) x (cost per breakdown) = (1.3) x (300) = RM390 per month Solution Step 3 Calculate Preventive Maintenance Cost
= cost of expected breakdown + cost of service contract = (1 breakdown per month x 300) + RM220 per month = RM520 per month Step 4 Compare Less expensive to suffer breakdown without service contract. Breakdown = RM390 Service contract = RM520 Therefore, continue present policy. Need to consider
Customer service Loss of production Loss of customer goodwill, reputation Machine life Availability of spare parts and expertise Safety to the user / customer
Trade is in bank deposits denominated in different currencies Law of One Price Example: American steel $100 per ton, Japanese steel 10,000 yen per ton If E = 50 yen/$ then prices are: American Steel Japanese Steel In U.S. $100...
famously suggested: "if cell A consistently contributes to the activity of cell B, then the synapse from A to B should be strengthened" ... Hebbian learning has all units the same. fixed output connections are inadequate. decorrelation: (indep for Gaussians)...
Velocity & Pressure. Flow Rates. As discussed previously in this course, velocity and fluid flow can have a great effect on corrosion. Systems should be designed to limit fluid flow velocities to levels that can be tolerated by the materials.
Quantifiers. We need quantifiers to express the meaning of English words including all and some: "All men are Mortal." "Some cats do not have fur." The two most important quantifiers are: Universal Quantifier, " For all," symbol: