Ch 31 IT-390Material Analysis

2 Material Substance being altered or used in an alteration Purchased (not manufactured) Materials required for a design - Bill of Materials (BOM) –Part list (type of material and quantity) Material details –Specifications - reside separately from the BOM

3 Material Raw, standard commercial items, subcontract items, interdivisional transfer –Raw Materials - Silica (sand) for glass manufacture –Standard Commercial Items - Nuts, bolts, screws, bearings,... –Subcontract Items - produced by an outside manufacturer –Interdivisional Transfer Materials - transferred between divisions of a corporation

4 Material Engineering, commodity, semi-engineering, and normative materials. –Engineering Materials - former commodities - have been substantially refined, such as aluminum, which is refined from bauxite. –Commodities - basic ores (bauxite, iron ore,...) –Semi-engineering Materials - gray area between commodities and engineering materials. –Normative Materials - price fixed through government intervention or cartels

5 Material Direct materials - go directly into the end product - come from the BOM. Indirect materials - necessary for conversion or manufacturing process - do not end up in the final product - (sand paper, cutting oil, cleaning solvents,...)

6 Shape Different approaches to Direct material estimation How much material (in weight or volume) - cost

7 Shape Theoretical approach –Appropriate for an injection molded plastic part or a die cast aluminum part –Allowances - Scrap, Waste, and Shrinkage. Scrap - faulty material - human error Waste - by-product of the manufacturing or conversion process Shrinkage - loss of material due to physical laws or theft (aging, oxidation, chemical reaction, spoilage,.)

8 Shape Second approach –Solid chunk of material - make mathematical subtractions Both approaches calculate the "shape" using geometry/trigonometry Shape - implies mass, area, or length - not the physical outline

9 Shape If complicated, cut it up and calculate separately, summing the results Cost of direct - reduced slightly by ability to sell waste material or recycle –Sawdust

10 Shape Efficiency- raw material - finished product –In this case, the shape yield could be calculated from formula 3.2 on page 88: –Es = St/Sa x 100% –Where:Es = shape yield –Sa = actual (original) shape in units of area, length, mass, volume, count, etc. –St = theoretical (final) shape required for design in units of area, length, etc.

11 Problem 3.19 a (pg. 120) What is the number of bars required? We will assume that both ends of the bar are faced From one bar we can cut: 144” – 6” = Bar length – Gripping = 8.36 units/bar 16”+1/16+1/16+3/8 Part length + Facing + Cutoff  8 units/bar Units required = % (scrap) + ½ % (shrinkage) = 264 units (260x.01 = 2.6, and 260x.005 = 1.3) Number of bars required = 264 / 8 = 33 bars required

12 Problem 3.19 b (pg. 120) What is the shape yield, Es? Es = St / Sa x 100% or Es = theoretical shape / actual shape x 100% Must calculate based on all =260  (1)² (16”) x (100%) = 87.5%parts and all bars required! 33  (1)² (144”) Remember, area of cylinders are expressed as  R²

13 Problem 3.19 c (pg. 120) 144”  R² 2” dia. What is the material cost per piece? Remember: part cost must not just absorb the part itself, but the waste also! Part Cost = Cost of bars / Total parts required =33 bars ( Cost per bar) 260 parts Part Cost = 33(96.02)=$12.19/unit Cost = (area)(length)(density)(cost/ lb ) Bar Cost =  (1 in.)² (144 in.) (.283 lb/ in³ ) ($.75/ lb ) = $96.02/bar

14 Handout Example Problem A part is machined as shown in the handout. The original stock size of AISI 1045 material is 5 X 2.5 X 2 in. Density = 0.29 lb/in 3. 1.If this material will cost $1.90/lb, then what is the unit cost of the raw material. (Before processing) 2.What cost is lost to waste given that the waste is salvaged at 10% of original value? 3.Find the shape yield.