Rapid Prototyping in China

Rapid prototyping is the automatic construction of physical objects with 3D printers, stereolithography machines, selective laser sintering systems, and other techniques, including:

• Fused deposition modeling
• Laser engineered Net Shaping
• Laminated object prototyping
• Thermal phase change inkjet and Photopolymer phase change inkjet

Traditionally these techniques have been used to produce models (prototypes). Nowadays, they are increasingly employed to produce tools or even to manufacture production quality parts in small numbers.

Selection of Techniques:

1. Rapid Tooling
- building an injection mold tool out of aluminum instead of steel and making moldings from production materials

PROS:

+ Produces production quality parts
+ Tools are good for (approx) 10,000 parts
+ The piece part price is very cheap

CONS:

- Tools are expensive to produce, and take relatively long

2. CNC Machining of all components
- use of Computer Numerical Control to control a milling robot

PROS:

+ Fast time to make one component
+ Very low setup cost

CONS:

- Limited range of materials (because of ease of machining and distortion issues)
- Components will usually be made from several section bonded together
- High piece cost

3. Silicon Mold
- CNC Machining of one component, and then copying that part using a cheap mould made of silicon rubber, which can make up to 16 components

PROS:

+ Fast

CONS:

- Limited range of materials can be molded in silicone (usually epoxy based)
- Parts do not have the same strength and flexibility as molded parts, snaps fitting may break for example, and the part would break in a drop test (meaning drop of table height ~ 1.20m)

4. SLS or SLA rapid prototyping
- Stereo Lithography: a laser hardens liquid into plastic, layer by layer

PROS:

+ Very fast
+ Low setup cost

CONS:

- High piece cost
- Material is not waterproof
- Absorbs water so changes shape over time
- Material is not flexible (will fracture if bent)

CNC and SLS/SLA are fast for the first part (normally taking about a week) but it then takes the same time to make each subsequent part, so for 16 parts this takes a relatively long time, and costs a lot. For an injection mould tool, it may take 2 or 3 weeks to make a tool, but then all parts can be molded in an hour or so, and the parts are much cheaper.

CNC machine tools offer improved automation. The operator intervention related to producing workpieces can be reduced or eliminated, as many CNC machines can run unattended during their entire machining cycle, freeing the operator to do other tasks.

A second major benefit of CNC technology is consistent and accurate workpieces. Today's CNC machines boast almost unbelievable accuracy and repeatability specifications. This means that once a program is verified, two, ten, or one thousand identical workpieces can be easily produced with precision and consistency.

A third benefit is flexibility. Since these machines are run from programs, running a different workpiece is almost as easy as loading a different program. Once a program has been verified and executed for one production run, it can be easily recalled the next time the workpiece is to be run. This leads to yet another benefit, fast change-overs. Since these machines are very easy to setup and run, and since programs can be easily loaded, they allow very short setup time.

Please contact Case Engelen at the Titoma Group for more information, a quick quote, or other inquiries: