Computer-aided manufacturing
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Computer-aided manufacturing (CAM) also known as computer-aided modeling or computer-aided machining
Overview
Traditionally, CAM has been
A CAM tool generally converts a model to a language the target machine in question understands, typically G-code. The numerical control can be applied to machining tools, or more recently to 3D printers.
History
Early commercial applications of CAM were in large companies in the automotive and aerospace industries; for example, Pierre Béziers work developing the CAD/CAM application UNISURF in the 1960s for car body design and tooling at Renault.[11] Alexander Hammer at DeLaval Steam Turbine Company invented a technique to progressively drill turbine blades out of a solid metal block of metal with the drill controlled by a punch card reader in 1950. Boeing first obtained NC machines in 1956, made by companies such as Kearney and Trecker, Stromberg-Carlson and Thompson Ramo Waldridge.[12]
Historically, CAM software was seen to have several shortcomings that necessitated an overly high level of involvement by skilled
The integration of CAD with other components of CAD/CAM/CAE
CAM packages could not, and still cannot, reason as a machinist can. They could not optimize toolpaths to the extent required of mass production. Users would select the type of tool, machining process and paths to be used. While an engineer may have a working knowledge of G-code programming, small optimization and wear issues compound over time. Mass-produced items that require machining are often initially created through casting or some other non-machine method. This enables hand-written, short, and highly optimized G-code that could not be produced in a CAM package.
At least in the United States, there is a shortage of young, skilled machinists entering the workforce able to perform at the extremes of manufacturing; high precision and mass production.[13][14] As CAM software and machines become more complicated, the skills required of a machinist or machine operator advance to approach that of a computer programmer and engineer rather than eliminating the CNC machinist from the workforce.
- Typical areas of concern
- High-Speed Machining, including streamlining of tool paths
- Multi-function Machining
- 5 Axis Machining
- Feature recognition and machining
- Automation of Machining processes
- Ease of Use
Overcoming historical shortcomings
Over time, the historical shortcomings of CAM are being attenuated, both by providers of niche solutions and by providers of high-end solutions. This is occurring primarily in three arenas:
- Ease in use
- For the user who is just getting started as a CAM user, out-of-the-box capabilities providing Process Wizards, templates, libraries, machine tool kits, automated feature based machining and job function specific tailorable user interfaces build user confidence and speed the learning curve.
- User confidence is further built on 3D visualization through a closer integration with the 3D CAD environment, including error-avoiding simulations and optimizations.
- Manufacturing complexity
- The manufacturing environment is increasingly complex. The need for CAM and PLM tools by the manufacturing engineer, NC programmer or machinist is similar to the need for computer assistance by the pilot of modern aircraft systems. The modern machinery cannot be properly used without this assistance.
- Today's CAM systems support the full range of machine tools including: wire EDM. Today’s CAM user can easily generate streamlined tool paths, optimized tool axis tilt for higher feed rates, better tool life and surface finish, and ideal cutting depth. In addition to programming cutting operations, modern CAM softwares can additionally drive non-cutting operations such as machine tool probing.
- Integration with PLM and the extended enterprise LM to integrate manufacturing with enterprise operations from concept through field support of the finished product.
- To ensure ease of use appropriate to user objectives, modern CAM solutions are scalable from a stand-alone CAM system to a fully integrated multi-CAD 3D solution-set. These solutions are created to meet the full needs of manufacturing personnel including part planning, shop documentation, resource management and data management and exchange. To prevent these solutions from detailed tool specific information a dedicated tool management
Machining process
Most machining progresses through many stages,[16] each of which is implemented by a variety of basic and sophisticated strategies, depending on the part design, material, and software available.
- Roughing
- This process usually begins with raw stock, known as terracesor steps, because the strategy has taken multiple "steps" down the part as it removes material. This takes the best advantage of the machine's ability by cutting material horizontally. Common strategies are zig-zag clearing, offset clearing, plunge roughing, rest-roughing, and trochoidal milling (adaptive clearing). The goal at this stage is to remove the most material in the least time, without much concern for overall dimensional accuracy. When roughing a part, a small amount of extra material is purposely left behind to be removed in subsequent finishing operation(s).
- Semi-finishing
- This process begins with a roughed part that unevenly approximates the model and cuts to within a fixed offset distance from the model. The semi-finishing pass must leave a small amount of material (called the scallop) so the tool can cut accurately, but not so little that the tool and material deflect away from the cutting surfaces.[17] Common strategies are raster passes, waterline passes, constant step-over passes, pencil milling.
- Finishing
- Finishing involves many light passes across the material in fine steps to produce the finished part. When finishing a part, the steps between passes is minimal to prevent tool deflection and material spring back. In order to reduce the lateral tool load, tool engagement is reduced, while feed rates and spindle speeds are generally increased in order to maintain a target surface speed (SFM). A light chip load at high feed and RPM is often referred to as High Speed Machining (HSM), and can provide quick machining times with high quality results.[18] The result of these lighter passes is a highly accurate part, with a uniformly high surface finish. In addition to modifying speeds and feeds, machinists will often have finishing specific endmills, which never used as roughing endmills. This is done to protect the endmill from developing chips and flaws in the cutting surface, which would leave streaks and blemishes on the final part.
- Contour milling
- In milling applications on hardware with rotary table and/or rotary head axes, a separate finishing process called contouring can be performed. Instead of stepping down in fine-grained increments to approximate a surface, the work piece or tool is rotated to make the cutting surfaces of the tool tangent to the ideal part features. This produces an excellent surface finish with high dimensional accuracy. This process is commonly used to machine complex organic shapes such as turbine and impeller blades, which due to their complex curves and overlapping geometry, are impossible to machine with only three axis machines.[19]
Software: large vendors
See also
- Computer-integrated manufacturing (CIM)
- Digital modeling and fabrication
- Direct numerical control (DNC)
- Flexible manufacturing system (FMS)
- Integrated Computer-Aided Manufacturing (ICAM)
- Manufacturing process management (MPM)
- STEP-NC
- rapid manufacturing– solid freeform fabrication direct from CAD models
- CNC pocket milling
References
- PMID 12014040.
- ^ "Method and apparatus for computer aided machining". 16 September 1997.
- PMID 18241215.
- ^ ISBN 978-1-4289-2364-5.
- ISBN 978-0-415-06314-2
- ISBN 978-0-19-860877-6.
- ISBN 978-0-8493-9418-8.
- ISBN 978-0-7506-5125-7.
- ISBN 978-3-540-55354-0.
- ISBN 978-1-57444-659-3.
- ^ Dokken, Tor. "The History of CAD". The SAGA-project. Archived from the original on 2 November 2012. Retrieved 17 May 2012.
- ^ Sanders, Norman. "A Possible First Use of CAM/CAD". Hal Portal Inria. Retrieved 30 October 2023.
- ^ Wright, Joshua. "America's Skilled Trades Dilemma: Shortages Loom As Most-In-Demand Group Of Workers Ages". Forbes. Retrieved 2023-04-14.
- ISSN 0099-9660. Retrieved 2018-06-02.
- ISBN 9788131729885.
- ^ CAM Toolpath Strategies. CNC Cookbook. Retrieved on 2012-01-17.
- .
- ^ Pasko, Rafal (1999). "HIGH SPEED MACHINING (HSM) – THE EFFECTIVE WAY OF MODERN CUTTING" (PDF). International Workshop CA Systems and Technologies. Archived from the original (PDF) on 2018-11-23. Retrieved 2018-06-02.
- .
Further reading
- Yong, Loong Tee; Moy, Peter K. (September 2008). "Complications of Computer-Aided-Design/Computer-Aided-Machining-Guided (NobelGuide™) Surgical Implant Placement: An Evaluation of Early Clinical Results". Clinical Implant Dentistry and Related Research. 10 (3): 123–127. PMID 18241215.
- https://patents.google.com/patent/US5933353A/en
- Amin, S.G.; Ahmed, M.H.M.; Youssef, H.A. (December 1995). "Computer-aided design of acoustic horns for ultrasonic machining using finite-element analysis". Journal of Materials Processing Technology. 55 (3–4): 254–260. .
External links
- CADSite.ru CAD Models
- Cimatron Brazil about Software CAD/CAM CimatronE
- Dragomatz and Mann reviewed toolpath algorithms in 1997.
- Pocket Machining Based on Offset Curves by Martin Held
- Purdue University Purdue Research and Education Centre for Information Systems in Engineering
- How to evaluate a CAM system Sheetmetalworld.com article