Bio-Medical Device Prototyping

Been noticed that people who want to get a prototype are not well known about the fabrication industry. What most people know about is 3D printing, seems it is the only way to get what they want. But it is not the truth at all. There are many techniques can be applied. Today I am going to share with you one of our production cases.

After a short conversation I released he need a prototype for this product first, follow by a small patch and then mass production. We know that 3D printing might be good for the prototype but is manufactured with the quantity that he needs in the future the pricing will be sky-high. Since Mr. Brain required 12 pcs of the prototype at the first production. Vacuum casting is the most ideal solution for it. It is a fast and high-quality way to make low volumes. And the quality of vacuum-casted parts is excellent, detailing fine surfaces from the original patterns.  Not only the final product needs assembly relationship checking, Masterpiece fitment is also important factor for the final assembly

Let's detail the process

Making the masterpiece

For a masterpiece, it must be as precise as possible, as all detail of your masterpiece will appear during manufacturing. Originally, Mr. Brain was a plan to do it with SLA(3D printing) but the accuracy is not up to expectation, therefore, we have changed it to CNC machining instead.

For the CNC it is “oversized” therefore we have to split and join. ABS is the most ideal material not only because it can be glued easily also suitable for most of the finishing process. As the vacuum casting parts will copy every detail of the Master Pattern, The Tolerance, appearance effect and assembly relationship of the Master will be checked and Inspected before maning molds.

Preparing the Silicone molds

Once the masterpiece is ready, and then built up molds for vacuum casting. Preparing these molds required us to pay attention to many important details including the following.

• Parting masking tape

Putting a tape around the masterpiece. The tape is transparent therefore will provide a clear vision during cutting.

• Draw parting lines

Draw a line on the masking tape which surrounds the masterpiece. This helps the process of parting the mold.

• Support

Help support the structure during the vacuum casting process.

• Vent

Prevent air bubbles from forming

• Mold frame 

Using the wooden board to be the mold frame.

• Fix the support

Additional support to make sure the mold is in the right position

• Mold Making

• Pour in a suitable amount of silicon into the ready mold frame.
• Vacuum the mold
• “Baking” the mold in constant temperature(Curing)

Removing the Masterpiece

After the molds were fully cured, the molds were opened according to the parting lines drawn previously and the piece removed. This job is trickier than it looks, and must be done with 100 % concentration otherwise the mold will be damaged and totaled. During the cutting, the sawtooth cut will be important for re-sealing the mold in the correct orientation when the molds are put back together for making copies.

Duplicate 

Once the molds are ready, they can be re-used up to twenty times to make identical copies of the original masterpiece. After that, they begin to degrade and need to be remade. When the molds were sealed, we poured liquid resin into the cavity and then placed the molds in a vacuum chamber for several hours while the resin cured.

Seems the story of Mr. Brain ends here, well still miles to go.

Finishing is a very important technic in the industries. It will showcase whether the customer has gotten what they wanted.

After the production, we have removed the unwanted part on the side of the parts.

•  Polish

In order to polish them evenly, we will spray them with black paint, so when the paint vanishes means the surface is readyto go. Not only the final product needs assembly relationship checking, 

• Primer

Adding the primer to the product is essential, it will help the surface of the product to be more even. And not all material has a good gripping ability, adding primer helps them stick better.

• l Surface treatment

Good appearance is definitely brightened up the end-user. There are many options at this point, gloss paint, flat paint, semi-gloss paint, and more. We have selected flat paint as appointed by Mr. Brain.

•  Logo printing

The final step, logo printing. There are many different ways to print the logo on the product. Silk screening is the most common option among all. For example, for metals we do process it with laser marking or anodise.