Hot Runner Mold
For almost 40 years, BMJ Mold and Engineering has designed, built, repaired and
worked on almost every type of mold existing in the plastic industry.
We produce high-quality injection molds for
cold runner,
insulated runner, and hot runner systems.
We are experienced in building and repairing molds for a variety of hot
runner systems, from manufacturers like:
- Husky
- Synventive
- Kona
- DME
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Learn more:
Choosing the Correct
Molding System
Hot-Runner Systems: The Pros and Cons
Primary advantages of hot runner systems include:
- Materials cost savings - no runner to regrind or reprocess
- Low cost / piece - least expensive for large volume
production
- Reduction of energy costs
- Shorter, faster cycle times - no runners to cool
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- 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
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Primary advantages of eliminating the runners include:
- No runners to remove or regrind
- Reduces the possibility of contamination
- Lower injection pressures
- Lower clamping pressure
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- Shorter cooling time
- Shot size reduced
- Cleaner molding process
- Eliminates nozzle freeze
- Consistent heat within the cavity
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There are, however, a few disadvantages to hot runner systems that
need to be considered:
- 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
- Risk of thermal damage to sensitive materials
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- Elaborate temperature control required
- Higher maintenance costs – more susceptible to:
- Breakdowns
- Leakage
- Heating element failure
- Wear caused by filled materials
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Learn more: Choosing
the Correct Molding System
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Hot Runner Molds: Efficient High Production
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:
- Part complexity
- Color requirements
- Physical characteristics of material
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- Type of material to use - virgin or "regrind"
- Color changes during production run
- Single or multiple design production
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The primary difference between hot runner and cold runner systems is that hot runner
eliminates excess material retained in feed channels of a cold
runner mold.
- Reduces the number of production steps required
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- Saves in material and energy costs
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Furthermore, hot runners use only 100% virgin resins; no reprocessed
or "re-grind"
material is added. This is an important feature for specific applications
where:
- Regrind can cause material to yellow
- Regrind can detracts from material properties, such as clarity in light pipe or lens production
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- Long-lasting transparency is a specific requirement
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Learn more: Choosing
the Correct Molding System
Hot Runner Molds: How They Work
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 systems shoot melted material directly into individual cavities
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- Hot runner molds are two plate molds with a heated runner system inside one half
of the mold
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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
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- The drops, situated perpendicular to the manifold, convey the
plastic from the manifold to the part
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Hot Runner Molds: Advanced Applications & Possibilities
Hot-runner systems are almost always used when large runs have to be
manufactured in highly automated production.
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; precise
computer-controlled timing allows for advanced processes, including:
- In-Mold Decoration – lamination with colored film coating
- Multi-Cavity Molds – cavities with different geometries and/or volumes
- Matching parts produced in one mold
- Injection valve opening and closing can be adjusted to the conditions of each individual cavity
- Injection pressure and holding pressure adjusted independently of each other
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- 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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For a quote or more information about how we can help your project, call 765-457-1166, or send us an email, or submit this short form:
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