Berk Korucu - 030080104 - 11th Week

1) Microhardness Test (Hardness Test)


There is no previous definition.



Current practice in the United States divides hardness testing into two categories: macrohardness and microhardness. Macrohardness refers to testing with applied loads on the indenter of more than 1 kg and covers, for example, the testing of tools, dies, and sheet material in the heavier gages. In microhardness testing, applied loads are 1 kg and below, and material being tested is very thin (down to 0.0125 mm, or 0.0005 in.). Applications include extremely small parts, thin superficially hardened parts, plated surfaces, and individual constituents of materials.


(H. Chandler, Hardness Testing  2nd Edition, p.3)


2) Special Indentation Test (Hardness Test)


There is no previous definition.



Special Indentation Tests: Modifications of this type test have been developed, and a few have had some commercial acceptance. Perhaps the best example is the Monotron test. This instrument used a 0.75 mm (0.03 in.) hemispherical diamond indenter. The Monotron principle was the reverse of the more conventional indentation testers such as the Brinell and Rockwell. Instead of using a prescribed force and measuring the depth or area, the Monotron indenter was forced into the material being tested to a given depth, and the hardness was determined by the force required to achieve this depth of penetration. This instrument was developed primarily for evaluating the true hardness of nitrided cases, which were, at one time, difficult to evaluate
accurately. The Monotron has not been manufactured for many years, and it is doubtful whether any are still in use.


(H. Chandler, Hardness Testing  2nd Edition, p.10)


3) Machining Costs (Accounting)


There is no previous definition.

The total cost of a machining operation includes contributions from some or all of the following components:

· Raw material costs: The cost of unmachined stock, which may be in the form of a standard bar or slab, casting, or forged blank · Labor costs: The wages for the machine operator, usually measured in units of standard hours · Setup costs: The cost of special fixtures or tool setups and the wages paid to setup personnel · Tooling costs: The cost of perishable tooling, including inventory, and any special tooling required for the operation · Equipment costs: The cost of the machine tools, including required capital expenditures, facilities costs, and machine depreciation · Scrap and rework costs: The cost of repairing or disposing of finished or partially finished parts of unacceptable quality · Programming costs: The cost of writing numerical control (NC) programs to generate the required toolpaths · Engineering costs: salaries paid to engineers for process design, validation, and other overhead functions.


(P. Andersen et al. , ASM Handbook vol 20 Materials Selection And Design, p.1771)


4) Early Cost Estimating (Accounting)


There is no previous definition.



The problem of estimating part and tooling costs before the part has been fully detailed is
discussed using machining as an example because this is one of the most common shape-forming processes. Several conventional cost estimating methods for machining are available both in handbook form, such as the Machining Data Handbook (Ref 18) and the AM Cost Estimator (Ref 19) and in software form. However, all of these methods are meant to be applied after the part has been detailed and its production has been planned, and they are not tailored for use by a designer. During the early stages of design, the designer will not wish to specify, for example, all the work-holding devices and tools that might be needed--a detailed design will not yet be available. Indeed, a final decision even on the work material might not have been made.


For early cost estimating an important assumption has to be made. The designer should be able to expect that, when the design is finalized, care will have been taken to avoid unnecessary manufacturing expense at the detail-design stage and that manufacturing will take place under efficient conditions.


To illustrate how such an assumption can help in providing reasonable estimates, consider the effect of the metal-removal rate on grinding costs, as shown in Fig. 6. These cost curves indicate that as the removal rate is increased the cost of grinding-wheel wear increases in proportion. At the same time, the cost of grinding decreases because the grinding cycle
is shortened; in fact, the grinding costs are inversely proportional to the removal rate.

(P. Andersen et al. , ASM Handbook vol 20 Materials Selection And Design, p.1558)