Product, Process, & Schedule Design

Dr. Rosario Rosas-Vega

IE 4355 : Facilities Design

Texas State University

Schedule Design

Schedule design decisions provide answers to questions involving how much to produce and when to produce.

Production quantity decisions are referred to as lot size decisions.

Determining when to produce is referred to as production scheduling.

How low production will continue?

Impact of Schedule Design

1. Machine selection

2. Number of machines 3. Number of shifts

4. Number of employees 5. Space requirements 6. Storage equipment

7.

Material handling equipment

8.

Personnel requirements

9.

Storage policies

10.

Unit load design

11.

Building size

Schedule Design

Process Requirements

Process design determines the specific equipment types required to produce the product. Schedule design determines the number of each equipment type required to meet the production schedule Specification of process requirements typically occurs in 3 phases:

1.

2.

3.

Quantity of components to be produced including scrap Equipment requirements for each operation

Combine the operation requirements

Calculation Production Requirements

Ik

Operation k Ok= Ik (1-dk) dkIk

Let:

dk = percentage of defective items produced on the kth operation. Ok = desired output without defects

Ik = production input

On the average:

For products with n sequential operations:

Example

• A product has a market estimate of 97000 components and requires three processing steps (turning, milling, and drilling) having scrap estimates of d1=0.04, d2 =0.01, and d3=0.03. What is the expected number of units to start

2

3

O3

production.

I1

1

Ik = Ok /(1-dk)

I3 = 97000 /(1-0.03)=100,000

I2 = 100,000 /(1-0.01)=101,000

I1 = 101,000 /(1-0.04)

=105,219

OR:

I1 = On /[(1-P1) (1-P2)…(1-Pn)]=

I1 = 97000/[(1-0.04) (1-0.01)(1-0.03)]=105,219

Productions Requirements with Rework

Example

The end product requirement is 100,000 pieces. Given that rework is performed, calculate the number of units required for processing at the first operation. Assume that the defective rates (in decimal) are d1= 0.03, d2 = 0.4, and d3 = 0.02.

100,000

I1

103,280

0.98 0.97 0.03 0.60

Equipment Fractions

Quantity of equipment required for an operation. F=SQ/HER

F = number of machines required per shift.

S = standard time (minutes) per unit produced. Q = number of units to be produced per shift. E = actual performance (%of standard time). H = amount of time (minutes) available/machine. R= machine reliability (% uptime).

Example

A machined part has a standard machining time of 2.8 minutes per part on a milling machine. During the eight-hour shift, 200 units are to be produced. Of the 480 minutes available for production, the milling machine will be operational 80% of the time. During the time the machine is operational, parts are produced at a rate equal to 95% of the standard rate. How many milling machines are required?

F=number of machines per shift

S=2.8 minutes per unit

Q=200 units per 480 minutes

E=0.95

H=480 minutes /shift.

R=0.80

F=SQ/HER=2.8(200)/0.95(480)(0.80) =1.535 machines per shift Facilities Design

7 Management and Planning Tools

Affinity Diagrams

Interrelationship Digraphs

Tree Diagrams

Matrix Diagrams

Contingency Diagram

Activity Network Diagram

Prioritization Matrix

Affinity Diagram

•

Gather and organize ideas and issues into groupings.

•

Uses techniques like brainstorming to get suggestions on how to solve the problems.

https://www.youtube.com/watch?v=ztTR8CKKS2Q

Interrelationship Digraph

•

•

•

Sequence of steps often comes from this activity.

Maps logical links among related items from Affinity Diagram.

Helps identify which items impact others the most .

Tree Diagram

•

Maps in increasing detail the actions that need to be accomplished in order to achieve a general objective

Matrix Diagram

Organizes information into sets for