DONGGUAN SINCERE TECH CO.LTD(SINCERE TECH) provides plastic injection mould solutions to industries of all types and sizes. For almost 20 years DST has designed, built, and worked on almost every type of mold existing in the plastic industry.
We are experienced in building custom Plastic molds for a variety of hot runner mold systems, from hot runner manufacturers like:
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Our state-of-the-art mold building facilities include High precision CNC machines, automatic CMM measurement machine, and Two heads of EDM Machines to create many types of custom molds, including complex specialty injection molds, insert molds, unscrewing molds, overmolding, gas-assisted injection molds, double injection molds (2k molding), etc. We can build molds for both cold runner systems and hot runner systems.
Each system offers advantages and disadvantages. Choosing the system to employ depends on the requirements of the part to be produced. A few of the considerations include:
Hot runner mold structure
Type of material to use – virgin or “regrind”
Colour changes during the production run
Single or multiple design production
Part complexity
Colour requirements
Physical characteristics of the material
The primary difference between the two systems is that the hot runner eliminates the excess material retained in the feed channels of a cold runner mold. This feature reduces the number of production steps required and saves in material and energy costs.
Furthermore, mostly hot runners use 100% virgin resins; no reprocessed or “re-grind” material is added. This is an important feature for specific applications where regrinding can cause the material to yellow, or detracts from the material properties, such as clarity in light pipe or lens production, where long-lasting transparency is a specific requirement.
hot runner with manifold
Hot runner direct gate
Hot runner molding systems normally inject melted material directly into the individual mold cavity. Hot runner is almost always used for large volume production of thermoplastic injection molded parts, or multiple part production using multi-cavity molds and stack-molding technology.
Hot runner molds are two plate molds with a heated runner system inside one half of the mold. A hot runner system is divided into two parts:
The manifold has channels that convey the plastic on a single plane, parallel to the parting line, to a point above the cavity
The drops, situated perpendicular to the manifold, convey the plastic from the manifold to the part
Primary advantages of hot runner systems include:
Shorter, faster cycle times – most of them have no runners to cool
Smaller machines – reduced shot volume into runners
Automated processing – runners do not need to be separated from the parts
Gates at the best position for economical design
Elimination of runners means
Materials cost savings – no runner to regrind or reprocess
Least expensive cost/piece
Reduction of energy costs
No runners to remove or regrind
Reduces the possibility of contamination
Lower injection pressures
Lower clamping pressure
Consistent heat within the cavity
Shorter cooling time
Shot size reduced
Cleaner molding process
Eliminates nozzle freeze
Hot runner molds are more complex and expensive to build than cold runner molds
Higher initial start-up costs than for cold runner systems
Complex initial setup prior to running the mold
Higher maintenance costs – more susceptible to:
Breakdowns
Leakage
Heating element failure
Wear caused by filled materials
Risk of thermal damage to sensitive materials
Elaborate temperature control required
The colors change is more complex than the cold runner, sometime you will spend lots of time and cost to clean up the hot runner systems, especially for transparency and white color parts.
Hot-runner systems are almost always used when large runs have to be manufactured in highly automated production. Additionally, technological advances enable us to build molds with gates positioned to yield the best quality molded parts.
Hot runner molds are sometimes connected to needle valve nozzles, which are activated with precise computer-controlled timing. This allows for a number of advanced processes, including:
In-Mold Decoration – lamination with a colored film coating
Multi-Cavity Molds – cavities with different geometries and/or volumes
Parts that belong together produced in one mold
Injection valve opening and closing can be adjusted to the conditions of each individual cavity
Injection pressure and holding pressure may be adjusted independently of each other
Controlled Volume Balancing – a weld line can be shifted into a non-critical area of the molded part
Stack Molding – two or more mold bases in production simultaneously creating multiple parting lines
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