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Overmolding
Applications
Since it is mostly welcome by all walks of life, the
dual application has turned into a trend in recent years. The international
brands are exploring the way to use shell molds to cover the products,
such as the handles of toothbrush, comb, cleaning brush, scissors,
torch, hair dryer, iron, electrical toothbrush. The covering of TPE
makes the product trendy and diversified. The market has been expanding
and it application is becoming wide.
Generally, the
dual-application injection has the following functions on product
design:
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To give the product surface a feeling of tenderness and comfort
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To provide a skid proof function of products
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To
increase the hardness of products to counter breaking
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To add value to current products and raise the quality of products
Methods
1. Multiple Material Molding
The multiple material molding is manufactured with multiple material
plastic injection molding machines (wide known as double injection
machines). The machines are generally in two different designs, including
vertical angle sandwich molding and horizontal sandwich molding. Vertical
angle double injection machines can cope with the operational pattern
of various dual colour molds, such as tractor type, supporting core
rotation, die core subsiding, valve separation, die core sliding etc.
Two (or more) plastics materials are injected into the different mold
cavities for the effect of multiple colours and materials.
The advantages
are as follows:
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The
production cycle is short, productivity will be higher than traditional
methods
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The
product quality is comparatively stable and the wastage is low
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The
adhesive force is relatively strong and the adhesion face is less
defective.
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It
can cater for dual material products in complex design
2. Insert
Molding
Insert molding is also called two steps method. It is manufactured
with horizontal and vertical injection machines. This method requires
two set of molds and two injection machines to use the stablise the
pre-cast hard plastic materials inside the cavity of the second mold
in the way of inserts. Then, it reaches the effectiveness of multi-colour
and multi-materials by injecting TPE on the hard plastic materials.
Examples
of joint finishing with PP bonding series
Joint
work of soft and hard materials
On the application of dual materials, different plastic
materials in hard nature can be applied in different products. For
example, PP is used in brushes and ABS, PC or PA are applied in home
appliances. As the feature of each specification and type of TPE is
different, and there may not be good adhesive power with a certain
TPE and all plastics materials, different TPE have to tailor for different
soft materials and various hard materials to achieve the best effectiveness.
What are the plastics
materials that can co-inject with TPE:
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PP, PE
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ABS, PC, ABS/PC Alloy
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PA66, PA+GF
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SAN,
K-RESIN, PS, HIPS, PMMA
More on Technical
and Factual Data:
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