Speedy
Mechanical
- Jun 5, 2001
- 229
Folks,
I am working on a project to produce a prosthetic product for trans-tibial amputees (below knee)
The product is tapered in the length direction and closed at the smaller end. It is circular in cross-section and thin-walled (5mm). It is approx 500mm in length and the larger outer diameter is 150mm (approx). A cross section has a 'U' shape.
A fabric is placed over the core of the mould and a soft elastomeric material is injected in through the bottom. For this stage there is no air evident in the product. The product is then removed from the mould and ‘ turned inside out’. It is put back on the core, the mould is closed and the product is re-formed with the fabric on the outside of the product. This is achieved by heating and then cooling the core.
Everything works fine, except for a small amount of air, which is trapped between the core and the product as it is turned. This manifests itself as a few air bubbles on the inner surface of the product. I have produced a number of products and all have this air bubble, regardless of how much I message the product and try to work the air out. I have even tried putting a small flexible pipe between the core and the product and drawing a vacuum but to no avail.
Any suggestions greatly appreciated!!
Speedy
I am working on a project to produce a prosthetic product for trans-tibial amputees (below knee)
The product is tapered in the length direction and closed at the smaller end. It is circular in cross-section and thin-walled (5mm). It is approx 500mm in length and the larger outer diameter is 150mm (approx). A cross section has a 'U' shape.
A fabric is placed over the core of the mould and a soft elastomeric material is injected in through the bottom. For this stage there is no air evident in the product. The product is then removed from the mould and ‘ turned inside out’. It is put back on the core, the mould is closed and the product is re-formed with the fabric on the outside of the product. This is achieved by heating and then cooling the core.
Everything works fine, except for a small amount of air, which is trapped between the core and the product as it is turned. This manifests itself as a few air bubbles on the inner surface of the product. I have produced a number of products and all have this air bubble, regardless of how much I message the product and try to work the air out. I have even tried putting a small flexible pipe between the core and the product and drawing a vacuum but to no avail.
Any suggestions greatly appreciated!!
Speedy
