A System for Automated Fixture Planning with Modular Fixtures

1.1. Background
1
Chapter 1
Introduction
Indusny has inmasingly paid more attention to the automath of nearly every facet of manufacturing in
order to eohrmce the quality of products and prcductivity. In addition, custom' ever-increasing demand
for rapid production has forced inmLsay to put more effort into automation than ever before. As a result,
industry wd computer-aided design (CAD) and computergided manufacturing (CAM) tools to
Suceesshrl)~ automate p t design, drafting. scheduling, and oIher step in various manufacturing processes.
Meral cutting is a labcr-intensive manufacturing prmm that requires expensive machine tools and highly
skilled human experts wih~ous hauds-onexperience,. In metal cutting, it has been a constant goal to
enhance productivity and meet the customer's demanl to pdwe be= quality pontr faster than before. In
recent years, there bas been much success in automating various metal cuniog pr0~esse.s. For example,
Compurpa numerically control (CNC) and dhX numerical ConmI~C) have in-d the productivity
of olachiac tools by pgmming NC codes at a disamce or from aremote terminal and downloading them
to machine tools. Also, NC oodes have beem aulamatidy gcllerared with an expat system resulring in
subsnmrial reduction in manual programming time [preiss 841.
Receotly. metal cutting indusaies have begu to experitnCe difliculty finding highly skilled machinists
because the number of apprentices is decnasing. It is l iy that the sinmion will worsen in the future
accmdbg to the trend. As a result, the need for automatiw of the metal cutting process has increased
rapidly.
Ooce he dimeasion of raw stock is determined to create apart, a metal Cuttiog prwsss can be divided
into two major activih 1) setup planning and 2) machining accr~dhg to setup plans. Setup planning lays
OUI the necessary metal CaUing operations to create the put from mw s a by determining the number of
setups and the w p sequence. In order to fully ~pmrmate a metal c&g pess. both the setup planning
and be actual cutting procedure must be automated. However, the complexity and many uncertainties in
the metal cuuing process have impeded the progress toward automafion.
The seulp in metal cutting specifies the orientadon and position of the part on the machine bed, a set of
feams to be cn~ a plan to cut each feature (We call this acutting plan), and aplan to locate the pan
accurately relative to the cutting tool and Md the part rigidly in position (We call this a fixture plan). A
cutting plan specifies the necessary cutting tools, tool paths, feed rate, and depth of cut, etc. A fixture plan