Hotmelts are more prone to voids, which could contain moisture. How is this avoided?

Hotmelts have a shrinking range between 7-9 %. For example, if you fill a plastic housing without pressure, you may get voids. This can be prevented by using a higher injection time on your hotmelt molding machine. That means if the mold is full and the material starts to shrink, you continue to fill material into the mold to overcome the shrinkage. The result is that you do not get voids and the shrinking of the parts is reduced to a range of 1-2 %.

Do hotmelts have to be applied at high temperatures? Some components are sensitive to prolonged exposure to high temperatures. What temperatures and times are involved with your material?

The temperatures you get on electronic parts depends on the design of the mold and the position of the runner. From our experience we know that the temperature on the electronic part is much lower than the injection temperature.

How do the costs of one- and two-component potting compounds compare?

When molding, you have in 90% of the cases a cycle time of 20-60 sec. You put your parts in the mold, inject the hotmelt, allow to cool, and then take the parts out of the mold. The part is now ready.
As there is no reaction you do not have to wait for any reaction of the material to take place. NO work in progress.

Do hotmelt systems have to conform to special design criteria for optimum performance?

The design is one factor in the success of a hotmelt molding project. Please look at our design guidelines "Construction Guidelines.pdf" and the explanation "filling of a housing.pdf".

Design Guidelines
filling of a housing

What is the operating temperature range?

You will also find the application temperature range in our product range. The optimum application temperature depends on the application and has to be tested for each application.

How long is a typical injection cycle?

The molding cycle is dependent on the size and material section thickness of the component. Typical cycle time ranges from 15 to 45 seconds and that can be for single or multi-cavity mold-sets.

Can material regrind be used?

For applications where the mechanical and adhesive properties of the material are critical, regrind should not be used. The regrind material will always contain a minute amount of mold release agent, which could compromise adhesive properties. Furthermore the mechanical properties of the material will degrade some from repeated re-melting. For non-critical applications the runners can simply be thrown back into the melt reservoir without any regrinding. It is strongly recommended to confirm that component molded from "regrind" material meets the final component specifications.

How do these Macromelt materials compare to engineered resins economically?

Macromelt does not replace other plastic materials directly. If a component can be molded successfully with PVC, there is no reason to consider Macromelt. If PVC molding results in high scrap levels as result of high pressure, low-pressure molding may be more economical as result of reduced scrap. More typically, the low pressure molding operation replaces several manufacturing operations such as molding of a plastic housing and potting with epoxy.

Can batteries be overmolded without reducing their effectiveness?

Many types of batteries have been successfully overmolded with Macromelt. However, a simple prototype overmold for a particular battery is recommended before starting full-scale production.

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