Hot runner molds are great. Everyone knows that. We eliminate runners, grinding them and reprocessing them. So what’s the issue? All hot runner molds are not created equal. We have all seen the application where using a hot runner mold resulted in more scrap and more regrind instead of its elimination. Why would this be? [...]
One of the basic requirements for successfully molded parts is that we must have cavity balance in order to achieve process robustness and fast cycle times that are necessary to be profitable in today’s competitive, global market. In this article we will take a basic look at good and bad cavity layouts and runner designs. [...]
There are three main runner shapes that are used: (1) full round (2) half round and (3) trapezoidal with each one having certain qualities and performances that may be needed to support delivery of the plastic to each cavity. […]
When selecting gate location (regardless of whether the tool features a cold or hot runner system), balanced and even filling of the molded part is the top priority. Cold runner gating provides the moldmaker with simplified integration in terms of selecting the optimal gate location, […]
Although a more expensive capital investment upfront, a hot runner system is a significantly more cost-efficient means to keep production costs to a minimum over the long run. […]
The cycle time of any mold is largely influenced by the cooling cycle—how fast the resin can be sufficiently cooled so that the part can be ejected without permanent deformation. In any given mold, the areas that take longest to cool are those with the thickest wall section. […]
The importance of runner analysis on design and molding seems to have been long overlooked. When many flow analyses are carried out, the focus tends to be mainly on the part and cavity. […]
Compression set is a phenomenon that causes most water leaks (not related to installation) in molds today. Simply put, this means that an o-ring has resided in a compressed state in the mold for so long that it has lost its ability to apply adequate force in the gland and overcome the applied water, air [...]
After an in-depth Web search and listening to numerous manufacturing reps speak in molecular detail, it is apparent that o-ring design/sealing is more complex than just a piece of rubber being squeezed between some tooling. […]
1) Static (stationary tooling) seals are o-rings placed between tooling or fittings that do not move—such as cores trapped and sealed between plates, or cavities housed in a bore with external o-rings that seal against the I.D or walls of the bore. […]