Build Anywhere Newsletter Vol.1 No.2

[Martin Hardwick]

This week we will begin a series of issues on the challenges 
of implementing STEP-NC. If you want to know more about STEP-NC 
try the virtual tours at www.stepnc.com or the resource pages 
at www.steptools.com/library/stepnc/index.html


------------------- 
Benefits of STEP-NC

Before discussing the challenges we should remind ourselves about 
the benefits.

- The ability to build parts anywhere because a STEP-NC part program 
  is a goal driven specification that can be compiled into codes 
  to run on any machine that meets the implied requirements of the 
  program.

- Improved safety and reliability because an intelligent STEP-NC 
  control can check the full definition of the part and machining 
  process for safety and quality violations before it begins 
  machining.

- Out-source quality control because a STEP-NC specification 
  includes a full description of the nominal geometry and 
  tolerances.

These benefits translate into reduced costs for data preparation, 
path planning, and machine set-up which in turn lead to reduced 
spindle time because more powerful machines can be applied to 
more ordinary jobs.



-------------------------------------- 
Challenge #1 Finding the Right Balance

A STEP-NC Part Program can be described on at least four levels. It 
is important to pick the right level, because if a STEP-NC program is 
too tightly described then a job shop will not be able to add value to 
the machining process, but if you leave too much flexibility in the 
program then you might not get the right part.

* LEVEL 1 - Macro-Planning Only 
At this level the STEP-NC file describes the final result of the 
machining operation but does not constrain the process used to 
achieve that result. 

For example, the surface finish and tolerance of a pocket are 
described, but the process does not specify how many roughing 
operations are required, how the tool should enter the pocket, 
and what strategy should be used to remove the material.


* LEVEL 2 - Micro-Planning 
At this level the STEP-NC file describes all the required 
operations but leaves details such as tool choices open for 
final selection by the job shop or intelligent controller.

For example, for the pocket the STEP-NC file may describe how the 
entry hole will be made as well as roughing and finishing steps. The 
tool selection and optimal speeds and feeds for each step are left to 
the discretion of the controller or job shop.


* LEVEL 3 - Tool Path Planning 
At this level every movement of the tool is described in the STEP-NC 
file to give the owner of the part absolute control over the process.

For example, the tools to be used to cut the roughing and finishing 
steps of the pocket are described in the file. The job shop must find 
cutting tools that match exactly and use these in a configuration 
(machine axes, clamps etc) that will not interfere with the chosen 
tool paths.


* LEVEL 4 - Device Code Planning 
At this level machine specific or machine independent codes are added 
to the STEP-NC part program to give the engineer control over these 
features of the machine. If a STEP-NC Part Program is similar to a 
C program, then this level of control is equivalent to inserting 
assembler codes into the C program. 

For example, to set up a probing pass for our pockets the engineer 
inserts device specific codes into the NC program. These codes are 
inserted because for reasons unknown the STEP-NC compiler is unable 
to generate the correct codes from the high level probing commands 
allowed in the STEP-NC language.



------------------------------- 
How to make Parts using STEP-NC

1. Go to the STEP-NC web pages at www.stepnc.com 
2. Take the "Virtual Tours". 
3. If you are a manufacturing engineer download the ST-Plan 
   plug-in and begin to use STEP-NC for operation 
   planning (you will need a desktop version of this 
   tool if you want to do professional level planning). 
4. If you are a CNC machining engineer download an 
   ST-Machine plug-in to find out how to intelligently 
   machine parts. 
5. Contact us to find out how to make this procedure a 
   regular part of your operations. 


------------------- 
Summary: 
Period Covered: Sun Sep 8 04:26:56 2002 -- Sun Sep 15 04:26:56 2002 
Total usage: 38 
Successful usage: 38 (100%) 
Errors: 0 (0%)

Translator total errors success rate 
ACIS to STEP: 12 0 100% 
STEP to ACIS: 3 0 100% 
AP203 Checker: 3 0 100% 
Parasolid to STEP: 6 0 100% 
STEP to Parasolid: 1 0 100% 
======================================= 
All-Time stats 
------------------------------------ 
Summary: 
Period Covered: Wed Dec 31 19:00:00 1969 -- Sun Sep 15 04:27:29 2002 
Total usage: 17272 
Successful usage: 15830 (91%) 
Errors: 1442 (8%)


--------------------------- 
Tools From STEP Tools, Inc. 

The world's foremost firms use the STEP Tools product line to help 
them share engineering product information. Over one million people 
use product data applications built with ST-Developer, the company's 
flagship product.

The STEP Tools vision is to enable digital manufacturing ANYWHERE 
using STEP-NC. With STEP-NC there should be no excuses. If your 
part data is in a STEP-NC format then it can be delivered on 
time, on cost and with the correct quality.

For a complete listing of the available products check out the STEP 
Tools web site at http://www.steptools.com


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