Product category:
CAM, CNC and production management software
News Release from: Pathtrace Engineering Systems | Subject: EdgeCAM software
Edited by the Engineeringtalk Editorial
Team on 02 November 2001
Waveguide manufacturing streamlined by
CAM system
At the heart of Elekta Oncology Systems' production unit for linear accelerator components is an EdgeCAM computer aided engineering programming (CAM) system
Elekta Oncology Systems is a company dedicated to providing solutions for minimally invasive neurosurgery and precision radiotherapy used in the treatment of tumours and as part of its expansion program, a manufacturing unit has been established to produce key elements for linear accelerators which are used in Intensity Modulated Radiotherapy (IMRT) At the heart of the production unit is an EdgeCAM computer aided engineering programming (CAM) system, supplied by Pathtrace of Reading, which is used to generate all the part programs required to machine sets of precision waveguide elements
This article was originally published on Engineeringtalk on 13 Feb 2001 at 8.00am (UK)
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Since its installation, EdgeCAM has not only improved control in terms of quality and repeatable accuracy but has allowed previous subcontract machining to be brought in house, manufacturing efficiency optimised, production costs trimmed and the supply of the various key elements secured.
Established in the summer of 2000 at Elekta's headquarters in Crawley, the waveguide manufacturing facility operates in a temperature controlled environment with a vertical machining centre, a high speed CNC lathe and a co-ordinate measuring machine (CMM).
Adjacent to the manufacturing unit is a large vacuum brazing furnace where the waveguides are joined together.
All part programs are generated using EdgeCAM for both the CNC lathe, which turns the shape for most of the element's profile and the machining centre for production of the 71 individual copper waveguide cell units which are stacked-up and brazed together to form the heart of the IMRT linear accelerator.
With new CNC machine tools being purchased, Elekta's engineers sought the most effective programming system which could use their design data.
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After careful study of the CAM market, the decision was made to install EdgeCAM which best met both current and future production needs as more jobs are being planned.
One of the engineers having a key role in the CAM selection process was waveguide technician John Jones.
"After looking at a number of different CAM systems the decision to buy EdgeCAM was based on a combination of its all-round performance, the power of the system, ease of use, communication capability and overall cost-effectiveness.
I was also impressed by the editing capabilities of the system and especially the area clearance routines on the milling module." These were most important to John Jones because each of the 71 waveguide cells are similar in external profile, however, the internal cavities progressively change in order to impart the necessary control and performance characteristics.
Produced from pre-machined copper forgings in two main operations involving turning and milling, each outer diameter of the wave guide cell element measures 100 mm.
However, they vary in length between 18 mm and 43 mm and the internal features, such as the main bore and the profiled radius cavity, may only vary by some 20 microns from adjacent cells in the stack.
The easiest solution when programming was to adopt the parametric programming facility within EdgeCAM, which required only the variable features to be entered for each individual cell into a master program for both turning and milling operations.
Not only has this considerably streamlined programming efficiency it has optimised machining times, which are around five minutes per side for turning and involves removing the bulk of the material.
Diamond tooling is used on both machines to produce the cells and tolerances are around ?0.01 mm with surface finish better than 0.2 Ra.
All key features are 100 per cent inspected on the adjacent CMM.
After a waveguide cell has been rough and finish turned using a Hembrug lathe, which features a hydrostatic slide and spindle, it is transferred to a specific position on a peg-type storage rack ready for manual transfer to the vertical machining centre.
This machine is equipped with a rotary fourth-axis indexing unit.
Milling operations typically relate to the production of four adjustment holes equally spaced around the periphery of the element, although some variants call for counterbored and threaded holes.
Usually angled at 60?, these 10 mm and 15 mm diameter holes are helically milled as conventional drilling could distort the internal face and reduce the performance of the cell.
Total cycle time for the production of these holes is eight minutes.
At present, Elekta's production schedules call for over 100 waveguide assemblies to be made each year.
This means that more than 7,000 individual cells have to be machined.
All programs are stored in EdgeCAM ready for downloading to the appropriate machine tool, which results in a very efficient program library solution.
With a number of new major machining projects likely to be handled by the waveguide facility at Crawley, EdgeCAM will soon be used for front line support creating the respective 2-D and 2?-D programs.
Maintains John Jones: "We have been well satisfied with the performance of EdgeCAM, the level of service and especially the online support we have received from Pathtrace.".
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