CAPP

Introduction to Computer Aided Process Planning : 

Introduction to Computer Aided Process Planning

Computer Integrated Manufacturing (CIM) : 

Computer Integrated Manufacturing (CIM) Computer Aided Design (CAD) 2D 3D Concurrent Engineering Computer Aided Process Planning (CAPP) Variant Generative Computer Aided Manufacturing (CAM) CNC Robotics Material Handling Just in Time (JIT) Group Technology Flexible Manufacturing Systems

What is process planning? : 

What is process planning? Recipe/Algorithm/Step-by-step instructions Fast Food Chain Same taste everywhere from NY to LA How do they do it? Customization in formal dinner restaurant

Manufacturing Environment : 

Manufacturing Environment Role of the master machinist in small batch manufacturing Manufacturing is more complex than cooking yet the planning for it is similar Job shop: group machines which perform same operation together Routing of parts through the various departments Process plan defines the route Reduction in the necessary skill of operator can be achieved by using a detailed process plan

Formal Definition : 

Formal Definition “Process planning can be defined as an act of preparing processing documentation for the manufacturing of a piece, part or an assembly” depending on the production environment can be Rough Detailed When process planning is done using a computer : “Computer Aided Process Planning”

Step-by-step operations in a sample part : 

Step-by-step operations in a sample part

Slide 7: 

Manufacturing a part to meet design specs. Selection of initial block Sequence of operations Selection of machine, process Surface finish Quality Tolerance Hardness Life Cost

A Rough Process Plan : 

A Rough Process Plan

A Detailed Process Plan : 

A Detailed Process Plan

Components of Process Planning : 

Components of Process Planning Selection of machining operations Sequencing of machining operations Selection of cutting tools Determining the setup requirements Calculation of cutting parameters Tool path planning and generation of NC/CNC programs Design of Jigs/Fixtures

Process Planning in different environments : 

Process Planning in different environments In tool-room type manufacturing “make part as per drawing” is sufficient In metal-forming type operations The process planning requirements are embedded directly into the die. Process planning is fairly trivial Job-shop type manufacturing requires most detailed process planning Design of tools, jigs, fixtures and manufacturing sequence are dictated directly by the process plan.

Requirements for process planner : 

Requirements for process planner Must be able to analyze and understand part requirements Have extensive knowledge of machine tools, cutting tools and their capabilities Understand the interactions between the part, manufacturing, quality and cost

Traditional process planning : 

Traditional process planning Experienced based and performed manually Variability in planner’s judgment and experience can lead to differences in the of what constitutes best quality Problem facing modern industry is the current lack of skilled labor force to produce machined parts as was done in the past Hence Computer Integrated Manufacturing and Computer Aided Process Planning

Advantages of CAPP : 

Advantages of CAPP Reduces the demand on the skilled planner Reduces the process planning time Reduces both process planning and manufacturing cost Creates consistent plans It produces accurate plans It increases productivity

Approaches to CAPP : 

Approaches to CAPP Variant Generative Automatic

Variant Process Planning : 

Variant Process Planning “based on the valid conjecture that similar parts will have similar process plans” Preparatory stage GT-based part coding Families of similar parts are created Family matrix A process plan is to manufacture the entire family is created

Variant Process Planning : 

Variant Process Planning Production Stage Incoming part is coded Part family is identified Process plan is edited to account for the different needs of the part Salient points of variant process planning Easy to build, learn and use Experienced process planners are still required to edit the process plan Cannot be used in an entirely automated manufacturing system without additional process planning

Variant Process Planning : 

Variant Process Planning

Generative Process Planning : 

Generative Process Planning “a system which automatically synthesizes a process plan for a new component” Requires Part description Part to be produced must be clearly and precisely defined in a computer compatible format (OPITZ,AUTAP) Manufacturing databases Logic of manufacturing must be identified and captured The captured logic must be incorporated in a unified manufacturing database

Generative Process Planning : 

Generative Process Planning Decision making logic and algorithms Decision trees Expert Systems: AI based approaches

Automatic Process Planning : 

Automatic Process Planning “ generate a complete process plan directly from a CAD drawing” Requires: Automated CAD interface Take a general CAD model ( 3D for unambiguous data) and develop an interface to develop a manufacturing interface for this model : Feature Recognition of CAD Design the parts with available manufacturing features : Feature based CAD Dual: useful features of both approaches Intelligent (computer based) process planner

Some process planning approaches : 

Some process planning approaches

References : 

References Systems Approach To Computer Integrated Design and Manufacturing Author: Nanua Singh Publisher: John Wiley & Sons Expert Process Planning For Manufacturing Author: Tien-chien Chang Publisher: Addison-Wesley Publishing Company