May 2011 Archives

The mold design is an intellectual work of realizing the idea of the mold so that the molded product is within the desired specifications and the cost is within the requested limit, and the items to be investigated can be classified into the following factors.

Functional design

- Maintaining the dimensions of the molded product
- Investigations of the runner and gate structure
- Investigations of the ejection method

Shape design

- Three dimensional shape design
- External appearance quality investigations (glossy surface, graining, etching, etc.)
- Investigation of shape transfer, etc.

Strength design

- Cavity and core deformation, breakage
- Deformation of the mold base, etc.

Thermal design

- Investigation of the thermal shrinkage with respect to the mold
- Investigation of the cooling capacity of the molded product
- Investigation of the temperature controlling means

Safety design

- Investigation of the hook bolt strength
- Investigation of the mold opening prevention structure, etc.

Maintenance design

- Investigation of the maintenance parts structure
- Investigation of spare parts
- Investigation of ease of disassembling and assembling
- Investigation of repeatability

Cost design

- Investigation of the mold cost
- Investigation of the molded product cost
- Investigation of using standard parts, etc.

Mold design is not merely creating a space for producing the shape of the molded product, but it is very important to carry out various studies from the above viewpoints.

Thermal insulation plates are very important components for stabilizing the temperature of the mold or injection molding and for realizing energy savings for temperature maintenance. These are used as mandatory components in the injection molding of engineering plastics or super engineering plastics.
At Misumi, we offer thermal insulation plates as a product line up from which you can select the plate to suit your application.

In general, the methods of using thermal insulation plates are the following two.

1.When using by fixing to the platen of the injection molding machine.
2.When using by fixing at the back of the mold mounting plate

The following items are the criteria for selecting thermal insulation plates.

1. Heat resistance temperature

As a guideline, the following recommended usage temperatures can be used.

-Recommended usage temperature of 100°C or less
-Recommended usage temperature of 180°C or less
-Recommended usage temperature of 220°C or less
-Recommended usage temperature of 400°C or less
-Recommended usage temperature of 500°C or less

2. Material

The material is related to the recommended usage temperature and the strength of compression.

The following are the types of materials used.

-Cotton cloth + phenol plastic (Bakelite)
-Craft paper + phenol plastic (Bakelite)
-Glass fiber + silicate powder
-Glass fiber + ultra heat resistant epoxy resin
-Glass fiber + phosphate powder
-Glass fiber + borate powder

Asbestos is not handled in Misumi because it is considered to be a human health hazard.

See enlarged view of the thermal insulation plate outline page

Texture is used for providing artificial undulation patterns or texturing on the surface of molded products.

"Texture" engraves undulations on the surface of the cavity similar to "etching", or "sandblasting".

In texture, etching, an acidic corrosive liquid is made to come into contact with and erodes the surface of the steel material under managed conditions.

When carrying out texturing, the technique is to pay attention to the following points.

(1) The surface roughness of the cavity surface should be polished as finely as possible.
Further, even the extent of polishing should be as uniform as possible.
When this is done, even the state of erosion of the undulations easily becomes uniform. If there are variations in the undulation pattern, the visual beauty perceived by the human eye may appear to be of a different nature. For example, the appearance of beauty seen under sunlight may be different from the appearance of beauty seen under the light of a white fluorescent lamp.

(2) The steel material should be of the same steel type as far as possible, and should be selected from the same lot.
If the steel type is different, the state of erosion may change in a subtle way. Even if the same erosion processing is done for SKD11 and the pre-hardened steel S55C, there may be subtle differences in the state of the undulations.
In addition, even if the same steel type is used, there is the danger of the finished state after texturing being different due to differences in the lot of the material or the direction of rolling of the material.
When a mold is prepared to yield multiple pieces of the product, or when there are many locations in which the mold is manufactured, or when the mold is produced simultaneously in Japan and other countries, it has been pointed out that there is the danger of the above cases occurring.
If the state of texturing becomes different, in order to carry out texturing again, it becomes necessary to carry out polishing again of the cavity surface which can lead to a huge loss of time.

(3) Particularly careful polishing is necessary for surfaces prepared by electric discharge machining.
Surfaces that are prepared by electric discharge machining will have a machining hardened layer that may have appeared, and hence it is recommended to carry out thorough polishing of such surfaces.