IT390 Material Analysis Ch 3 1 Material Substance

IT-390 Material Analysis Ch 3 1

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 2

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 3

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 4 government intervention or cartels

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, . . . ) 5

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

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, . )7

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 8

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 9

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. 10

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” = 16”+1/16+3/8 Bar length – Gripping = 8. 36 units/bar Part length + Facing + Cutoff 8 units/bar Units required = 260 + 1% (scrap) + ½ % (shrinkage) = 264 units (260 x. 01 = 2. 6, and 260 x. 005 = 1. 3) Number of bars required = 264 / 8 = 33 bars required 11

Problem 3. 19 b (pg. 120) What is the shape yield, Es? Es = St/Sa x 100% =260 (1)² (16”) 33 (1)² (144”) or Es = theoretical shape/actual shape x 100% Must calculate based on all x (100%) = 87. 5% parts and all bars required! Remember, area of cylinders are expressed as R² 12

Problem 3. 19 c (pg. 120) 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)=$12. 19/unit 260 144” R² 2” dia. -------Cost = (area)(length)(density)(cost/lb) Bar Cost = (1 in. )² (144 in. ) (. 283 lb/in³) ($. 75/lb) = $96. 02/bar 13

Handout Example Problem • A part is machined as shown in the handout. The original stock size of AISI 1045 material is 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. 14