ENGINEERING MANAGEMENT GE 406 Chapter 6 Manufacturing Process Selection and Design Dr. Ibrahim Suleiman
Types of Processes Last chapter we classified process according to their design. We had single and multiple-stages. We also have make to stock and make to order processes as well as a combination of these processes. Another way to do that is to see what the process does, therefore, we have: 1. Conversion processes: such as changing the iron into steel sheets or making all the ingredients listed on the box of toothpaste into toothpaste. 2. Fabrication processes: such as changing raw materials into specific form. For example, making sheet metal into a car fender. 3. Assembly processes: such as assembling a fender to a car. 4. Testing processes: they are not actual processes, but they are widely mentioned as a stand-alone major activity.
Process Flow Structure Job shop: Production of small batches of a large number of different products. As for commercial printing firms, machine tool shops Batch Job: Essentially, a somewhat standardized job shop. This applies when we have a stable line of products, each of which is produced in periodic batches. Assembly line: Production of discrete parts moving from workstation to workstation at a controlled rate. Examples include: manual assembly of toys and appliances Continuous flow: as in conversion or further processing of undifferentiated materials such as petroleum, chemicals or Pepsi. As for the assembly line, the production follow predetermined sequence of steps, but the flow is continuous rather than discrete.
Product Process Matrix The relation ship between process structures and volume requirements Is often depicted on a productprocess matrix. The way to interpret this matrix is as volume increases and the product line narrows, specialized equipment and standardized material flow becomes economically feasible
Break Even Analysis Specific process equipment selection A specific approach to choosing among alternative processes or equipment is break even analysis. A break even chart visually presents alternative profits and losses due to the number of units produced / sold. The choice obviously depends on anticipated demand. The method is most suitable when processes and equipment entail a large initial investment and fixed cost, and when variable costs are reasonably proportional to the number of units produced. The Figure shows an example of a break-even chart.
Decision Variables in Equipment Selection
Break-Even Analysis Solution: First, we determine the relations between the cost and the demand 1- If the manufacturer decided to buy the part, then: Purchase cost = $200 Demand 2- If the manufacturer decided to make the part using a semiautomatic lathe, then: Produce using lathe cost = $80,000+$75 Demand 3- If the manufacturer decided to make the part using a semiautomatic lathe, then: Produce using machining center = $200,000+$15 Demand
Break-Even Analysis Second, we draw these relations in the so called break - even chart The relations are shown in the Figure below Purchase cost = $200 Demand lathe cost = $80,000+$75 Demand machining center = $200,000+$15 Demand $ 2.5 2 1.5 3 x 105 1 Purchase cost Purchase Semiautomatic cost Lathe Semiautomatic Machine center Lathe $ 200,000 $ 80,000 0.5 640 units 2000 units 0 0 500 1000 1500 2000 2500 Number of Units
Break-Even Analysis The figure on the right shows the break even point for each process. The break even point B calculation is The solution space is If demand <640 buy option is the best 640 < demand <2000 semiautomatic machine is the cheapest Demand >2000 machine lathe center is the cheapest The break even point A calculation is Th e least total co st line is high ligh ted b y RED as seen in th e Figure The least cost line
Break Even Analysis (Continue) Consider the effect of revenue, assume the parts sells for $300 each. Profit is the vertical distance revenue line and the alternative total cost. For example: at 1000 units demand, maximum profit is the difference between $ 300,000 revenue and (point C) and the semi-automatic lathe cost of $155,000 (point D)- at this demand level the semiautomatic machine is the least cost option. Break even chart The least cost line
Manufacturing process Flow design Manufacturing process flow design is a method to evaluate the specific process that raw materials, subassemblies, and parts follow as they move through the plant. The most common production management tools are: assembly charts, route sheets, flow process charts. Assembly drawing is an exploded view of the product showing its components parts Assembly chart uses the information from the assembly drawing and defines how parts go together, their order of assembly and often the over all material flow pattern
Manufacturing process Flow design Operation and route sheet :- specifies operations and process routing for a particular part Process flowchart denotes what happens to the product as it progresses to the productive facility
Example Manufacturing Process Analysis
Manufacturing Process Analysis SOLUTION
Manufacturing Process Analysis
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