Title: Identifying Constraints.
1Identifying Constraints
2Contents
- Introduction.
- Theory of Constaints.
- Features of Constraints.
- Constraints vs Objectives.
- Combined Objectives - Constraints Tree.
- Examples.
3Constraint
4Constraint
5Theory of Constraints
- An overall management philosophy introduced by
Eliyahu M. Goldratt in his 1984 book titled The
Goal. - Goldratt adapted the concept to project
management with his book Critical Chain,
published in 1997. - The rate of goal achievement by a goal oriented
system (i.e., the system's throughput) is limited
by at least one constraint.
6Theory of Constraints
- If there was nothing preventing a system from
achieving higher throughput (i.e., more goal
units in a unit of time), its throughput would be
infinite which is impossible in a real-life
system. - Organizations can be measured and controlled by
variations on three measures throughput,
operational expense, and inventory.
7Constraints and Goals
- Only by increasing flow through the constraint
can overall throughput be increased. - Identify the system's constraint(s).
- Decide how to exploit the system's constraint(s).
- Subordinate everything else to exploitation
decision(s). - Alleviate the system's constraint(s).
- If in the previous steps a constraint has been
broken, go back, but do not allow inertia to
cause a system's constraint.
8Constraint Cycle
9Misidentifying a Constraint
You thought the real constraint is upstream!
10Dealing with Constraints- Adding Capacity
Upstream
11Misidentifying a Constraint
You thought the real constraint is downstream!
12Dealing with Constraints- Adding Downstream
Capacity
13Focusing Steps
14Design Constraints
- A limit or restriction on the designs behaviors
or attributes. - Identifying limits that cannot be exceeded and
boundaries that may not be crossed. - Are there things or circumstances you want us to
avoid? - Framed as a binary yes-or-no choice.
- Limit the size of a design space.
- Exclusion of unacceptable alternatives.
15Safe Ladder Constraints
Constraints as a kind of checklist. Keep our
list of possible designs to a reasonable
length. May be expressed in terms of specific
numerical values.
16Juice Container Constraints
17Constraints vs Objectives
Constraints Objectives
Limit the size of the design space. Permit to explore what remains in that design space
Enable us to reject unacceptable alternatives. Enable us to select among design alternatives that are at least acceptable
Designs that satisfy are accepted. Designs that satisfice may not be optimal or the best.
18Constraints vs Objectives
- Design an affordable toy vehicle using
biodegradable material alone. - Objective To design a toy vehicle, should be
affordable. - Constraint Use of biodegradable material.
- Cost can become a constraint (say below Rs.
25/-). - Objectives are desirable attributes.
- Constraints are required attributes.
19Objectives Tree-Juice Container
20Combined Objectives and Constraints Tree - Juice
Container
Constraints in Italics Boxes differently shaped
21Combined Objectives and Constraints Tree
- Combined Tree communicates how objectives and
constraints interact. - Constraints are related to but are different from
objectives. - Constraints help us prune or narrow our space of
designs. - Constraints help us do our screening and
evaluation of designs.
22Constraints
- Design of a widely used product to be done in a
more constrained design space than client- or
user-specific devices. - Constraints lists prepared by different teams may
differ rather markedly. - Different teams may identify different limiting
values for the same constraint. - Constraints may sound binary or fuzzier.
- There may be differences in granularity.
23List of Constraints for an Arm Support Team A
MORE GRANULAR
24List of Constraints for an Arm Support Team B
Compact
25Types of Constraints
Affected Parameter?
26Reference
- Clive L Dim, Patrick Little and Elizabeth J
Orwin, Engineering Design, A Project Based
Introduction, 4th Edition, Wiley, U.S.A, 2014. - https//medium.com/praxis-blog/theory-of-constrain
ts-106-the-five-focusing-steps-741f1b770bf1
27Thank You