1. Chapter 4
Process Design

2. Objectives
After reading the chapter and reviewing the materials presented the students will be able to:
Understand the role of process design in facilities planning
Construct routing sheets
Balance an assembly line

3. Introduction
The process designer determines how the products and all its components will be made. It would include the following:
1. The sequence of operations to manufacture every part in the product.
2. The needed machinery, equipment, tools, fixtures, and so on.
3. The sequence of operations in assembly and packaging.
4. The time standard for each element of work.
5. The determination of conveyor speeds for cells, assembly and pack out lines, and paint and other finishing systems.
6. The balance of workloads of assembly and pack out lines.
Load work cells.
8. The development of workstation drawing for each operation using the principles of motion economy and ergonomics.

4. Fabrication: Making the Individual Parts
The sequence of steps required to produce (manufacture) a single part is referred to as routing.
The form used to describe this routing is called a route sheet.
A route sheet is required for each individual fabricated part of the product.
The route sheet lists the operations required to make that part in the required sequence (fig 4-1,2 page 98).
A copy of the route sheet would be issued by the production and inventory control department showing the order quantity.
This order would then be given to the stores department where the raw material would be pulled and transported to the first operation (according to the route sheet).
The route sheet would accompany the material from operation to operation telling the operator what to do.
The route sheet ends with the last operation prior to being assembled with other parts.

5. The Number of Machines Needed
The questions of how many machines you should buy can be answered only when you know:
1. How many finished units are needed per day.
2. Which machines run what parts.
3. What is the time standard for each operation.
The marketing department decides how many products to produce (manufacture) per day.
Once all the machine requirements for each operation have been calculated, total similar machine requirements and round up recommending the purchase of enough machines (fig 4-4, page 102).
This information on the number of machines required will be used later to determine the number of square feet of floor space needed in the fabrication department.

6. Work Cell Load Chart
Group technology takes advantage of similarity in parts or features in a group or family of parts so that these parts can be processed as a group.
A work cell is a collection of equipment required to make a single part or a family of parts with similar characteristics.
This equipment is placed in a circle around an operator or operators (fig 4-5, page 103).
The work cell concept considers operator utilization to be more important than machine utilization.
Work cell load charts list the operators time, machine time, and walking time required to run a work cell to produce one part per cycle using many machines (fig 4-6, 7 page105, 106).
The work cell load charts show the total cycle time, operator utilization, and machine utilization.

7. Step by Step Procedure for Preparing a Work Cell Load Chart
1. Operation No: This is a numerical sequence of steps like 1, 3, 5, 7. This will allow the insertion of new operations without having to renumber everything.
2. Operation Description: This will include machine names and operations being performed.
3. Manual: The time it takes the operator to load, unload, inspect and do anything else the operator is supposed to do.
4. Machine: This machine time is calculated using feed and speed formulas.
5. Walk: The time it takes the operator to move form one machine or operation to the next. The time standard is .005 minute per foot.
6. Operation accumulation time graph (fig 4-6, page 105): The time data are plotted on the chart using 3 standard symbols: solid line for manual or operator time, dotted line for machine time, and zigzag line for walk time to next operation.
With analysis and imagination, improvements can be attained.

8. Assembly and Packout Process Analysis
The Assembly Chart (fig 4-8, page 108): The assembly chart shows the sequence of operations in putting together the product. Time standards are required to decide which sequence is best. The process is known as assembly line balancing.
Time Standards for Every Task (fig 4-9, page 108): The task should be as small as possible, so that the layout designer has the flexibility of giving the task to several different assemblers.
Plant Rate and Conveyor Speed: Conveyor speed is dependent on the number of units needed per minute. Conveyor belt speed is recorded in feet per minute. The size of the part, plus the space between parts (measured in feet) times the number of parts needed in one minute equals feet per minute (see example on page 109).

9. Assembly Line Balancing
The objective of assembly line balancing is to give each operator as close to the same amount of work as possible.
In an assembly line mode, the operations are slowed to the rate of the slowest activity.
Packout work is considered the same as assembly work as far as assembly line balancing is concerned.
Many other jobs may be performed on or near the assembly line, but they are considered as subassemblies. Their time standards stand on their own merit.

10. Step by Step Procedure for Completing the Assembly Line Balance Form
The assembly line balancing form (fig 4-14, page 116) includes the following:
1. Product No.: The product drawing or product part number.
2. Date: The completion date of the development of this solution.
3. By I.E.: The name of the industrial engineer doing the assembly line balance.
4. Product Description: The name of the product being assembled.
5. Number of Units Required per Shift: Given by the sales department.
6. Takt time: The plant rate (R value). Existing products have 85% efficiency. New products average 70% efficiency during the first year.
7. No.: This is the sequential operation number.
8. Operation/Description: A few well chosen words can communicate what is being done at this workstation.
9. Takt Time: The takt time is calculated for each operation.
10. Cycle Time: The cycle time is the time standard for a job.
11. No. of Stations: The number of stations is calculated by dividing the takt time into the cycle time and rounding up.
12. Average Cycle Time: The average cycle time is found by dividing the cycle time by the number of workstations. It is the speed at which the workstation produces parts.
13. % Load: The % load tells how busy each workstation is compared to the busiest workstation.
14. Hrs./1000 Line Balance: The hours per unit can be calculated by dividing the average cycle time by by 60 minutes per hour.
15. Pcs./Hr. Line Balance: Divide the hours per unit into 1.
16. Total Hours per Unit: Add the number of hours from all the operations.
17. Average Hourly Wage Rate: This would come from the payroll department.
18. Labor Cost per Unit: The lower the cost, the better the line balance.
19. Total Cycle Time: Tells the exact work content of the whole assembly.

11. Calculating the Efficiency of the Assembly Line
Remember not all stations are performing at their maximum capacity.
A operator can only work as fast as the slowest member of the team.
Line efficiency = (sum of 1 cycle time/ total cycle time) * 100

12. Use of Computer Simulation
Computer simulation and modeling are powerful tools in designing work cells and aiding with balancing lines and work cell loads.
Computer simulation packages such as ProModel (fig 4-15, page 120) allow the designer to play with various scenarios in order to optimize the cell.

13. Layout Orientation
Mass production is product oriented and follows a fixed path through the plant.
The job shop orientation layout is process oriented (built around machine centers).
A work cell is a group of machines dedicated to making one complicated part. One or two operators may run 6 to 10 machines.

14. Summary
The process designer determines how the products and all its components will be made.
The sequence of steps required to produce (manufacture) a single part is referred to as routing.
The route sheet lists the operations required to make that part in the required sequence.
The questions of how many machines you should buy can be answered only when you know: 1. How many finished units are needed per day. 2. Which machines run what parts. 3. What is the time standard for each operation.
A work cell is a collection of equipment required to make a single part or a family of parts with similar characteristics.
The assembly chart shows the sequence of operations in putting together the product.
The objective of assembly line balancing is to give each operator as close to the same amount of work as possible.
Computer simulation and modeling are powerful tools in designing work cells and aiding with balancing lines and work cell loads.
Mass production is product oriented and follows a fixed path through the plant.
The job shop orientation layout is process oriented (built around machine centers).
A work cell is a group of machines dedicated to making one complicated part. One or two operators may run 6 to 10 machines.

15. Home Work
What is the role of a process designer in facilities planning?
What is the purpose of the route sheet?
What is a work cell?
What is the objective of assembly line balancing?