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CNC rapid prototyping

Everything You Need To Know About Metal Rapid Prototyping

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The machining of parts is carried out with the help of computers capable of controlling the machinery. And with the emergence of CNC rapid prototyping machining, it was possible to automate this process thanks to the ease of control by a computer program with minimal human intervention.

Its use expands to assembly operations, inspection, work on metal sheets, among others. It can be applied to any field, CNC or numerical control machining is used more than anything in metal or aluminum machining processes such as drilling or milling. Thanks to its automation capabilities, manufacturing proceeds at an accelerated rate and produces more accurate results.

How did CNC machining come about?

CNC machining emerged in 1940 thanks to the work carried out by the American engineer John T. Parsons, who used punched cards as a position coordinate system to control a machine center. Eight years later, this system was presented to the US Air Force to be sponsored in the laboratories of the Massachusetts Institute of Technology (MIT).

By 1952, MIT created the first prototype of a CNC rapid prototyping machining and, shortly after, it was introduced into machine tool factories for the production of metal parts, while they continued their research to provide the programmer with the means necessary to communicate part machining instructions to machinery in an easier way.

Types of machines that work with CNC rapid prototyping

Among the most common CNC machines are milling machines, grinding machines, and lathes. Milling machines are automatic cutting machines capable of working even with metals. Lathes are automated tools that rotate on their axis to shape the material. Grinders, for their part, use abrasive discs to perform abrasive machining on metal or plastic. These machines are easy to program and are used in CNC machining projects that do not need as much precision.

Numerical control machining technology contains information related to the position where the machine parts are to be placed. Currently, most of these tools are connected to a computer network where they receive all the instructions.

Advantage

CNC metal prototype machining encompasses the processes of CNC turning, CNC milling, wire cutting and EDM, being ideal to satisfy the vast majority of needs in terms of product development, always starting from the geometry defined by a 3D file. Here are some of benefits:

  • Highly accurate
  • Obtaining tight tolerances
  • Suitable for most materials
  • Optimal surface finish.
  • Low investment in setup costs
  • Scalable volumes from 1 unit
  • Production agility

CNC metal prototype machining applications

Thanks to the automation of CNC metal prototype machining, its use was extended to different industrial sectors such as wind power, aeronautics and even rail, where CNC milling machines perform the molding of landing gears and fuselage components. Many industries turn to the CNC metal prototype machining center to combine different operations on the same machine. Of course, it is necessary for it to meet the needs of roughing, semi-finishing and part finishing operations using multiple heads with automatic change.

CNC rapid prototyping

Tempocast and Tempoform technology

Through these two processes, we can manufacture parts in Aluminum, Magnesium, and Zink or Zamak. This technology starts from a plastic prototype manufactured by 3D printing metal or resin CNC machining. With these cores we manufacture as many negatives as we need depending on the number of metal pieces to cast.

The negatives are made with a material called “plaster” that is deposited in a liquid state. After a drying process, it is prepared for the casting of the liquid metal and once it has been cast and hardened, the imprint is destroyed for remolding. This is the reason for manufacturing as many traces as parts to cast.

Tempocast technology allows us to obtain surface finishes and dimensional tolerances similar to aluminum injection. There is the possibility of making pieces from 50 to 1000 copies. The thickness of the piece has to be 1mm minimum. Piece dimensions from 10 x 10 x 10 mm to a maximum of 1500 x 1500 x 1000 mm.

The Tempoform process is identical to the previous one, but as an initial prototype, a faster and cheaper 3D printing metal is used to produce as many models as we need footprints. This technology is aimed at series from 1 to 50 pieces and with surface finish requirements similar to sand casting or sintering. The maximum dimensions of these pieces are 340 x 340 x 600 mm.

prototype model

Does Prototype Equal to The End Product ?

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prototype model

 

Today ,When people are talking about rapid prototyping ,usually it’s involved in a question: is the prototype same as the end product ? especially on the function and performance of material .Most of designer or engineers have expressed concern about this question, in fact ,we should treat this question dialectically. That means it depends on what type of prototypes you discussed .Hereby ,as a prototyping manufacturer ,we are mainly discussing three pointing as below:

 

 

 3D Printing Prototype

As we all know. It is formed by resin or metal powder layer by layer for 3d printing prototype ,including SLA ,FDM ,etc .The principle of prototype manufacturing is the same. Obviously these procedures are totally different from the mass production in molding ,and also ,the materials of features and performance are a little bit different too .So we can say 3D printing prototype is not the same as the end product .However , in some industries,3D printing can not be replaced ,such as : in jewelry and medical sector ,due to the particularity of the industry, in most cases, customers demand to develop small and irregular shaped product with low volume manufacturing ,it’s a not good choice by molding or impossible , thus ,3D printing is a good option ,or it is necessary .In this situation, the prototype is just the final product .

Vacuum Casting In Soft Tooling

It’s a process of using RTV molding to cast plastic and rubber prototype parts .In this sector ,usually the material of prototypes are collectively called PU. There are some materials similar with ABS ,Nylon ,POM…etc .But they are not the real end product materials .The type of rapid prototyping process can produce low volume products quickly .RTV molding is silicone soft tooling ,it can save so much money and time to compare with steel molding .Is this type of prototype treated as the end product ? It had better check with the prototyping company where your product applied is ? what condition does the product work ? Usually for the housing shell of consumer electronics product with the short run requirements.It can be replacement totally.

CNC Prototype Machining

In most cases ,we can say this type of CNC prototyping is almost the same as the end product .Because no matter on prototype or final production phase ,both processes are not changed too much,they are all CNC manufacturing ,unless a bit difference on both efficiency and production cost ,such as: in the final production stage ,the vendor will add up more fixtures or  automation equipment ,or customers just request the finished of prototype as machined in order to save the cost ,but for later mass production ,they want a nice finished ,for example : anodized ,plated ,powder coated ..etc. However ,the manufacturing essence has not changed. There are two points as following worth discussion individually :

(1) CNC Metal Prototype :

For most metal products of industries ,the shape and structure is simple ,once the engineers confirmed the plan to create CNC prototype , then ,the final production will also be CNC machining way.We can say that the prototype equals to the end product due to both taking the same manufacturing process . Of course ,some of metal product is special and exclusive ,such as : the shell of automobile engine,in the beginning of product development test step ,building prototype in CNC , but for later mass production .Obviously it’s the best choice by molding due to the structure is quite complicated ,the production cost will be increase greatly in CNC machining , it dose not make any sense.

(2) CNC Plastic Prototype:

basically there are two cases custom plastic prototype ,one is for big prototype model in ABS or Polycarbonate ,ABS is the most commonly engineering  material ,and it’s the cheapest too .So when building a big model ,it can be split in a few small pieces and glue again after that in order to save the cost .It’s convenient to handle this process .Obviously it can not equivalent to the final product .Another one is for the stiff engineering material ,such as: Acetal/Delrin, PEEK. People must take CNC  because of 3D printing limitation for using material currently,if short run production for later requirements , It is still the best choice by CNC machining .At the moment ,plastic machining is playing more and more important role in rapid prototyping industry .

Conclusion

According to the analysis and statement above ,how to judge if the prototype equivalents to the final product ? It will depend on many factors : material ,application,manufacturing processes ..etc. If you are not sure ,then ,you had better check it with the manufacturer along with your design and details .They will answer you from a professional perspective。