Garage Equipment World are a independent garage equipment supplier company
Wednesday, September 26, 2012
Multi shot molding improves product quality
Multi shot molding is a process in which a number of separate material
shots are used to produce the final product. Movement of the molding
tool and the molded part can allow two, three and even four-shot
processes. Multi shot molding is also called in-mold assembly, because
the resulting part consists of two or more pieces made of different
materials that would normally be joined in a downstream assembly
operation.Multi shot molding is widely used to make products that fit in
the hand. In the medical device industry, these include small
drug-delivery systems and various handheld metering and diagnostic
devices. The medical industry has been slow to embrace multi shot
molding, but appears to be gradually gearing up to this complex, costly,
but highly capable process.China Composite Resin - Construction Structural Adhesive for Anchoring (Tube) ManufacturersProducts
made by multi shot processes combine the characteristics and properties
of two or more different materials.By eliminating assembly steps, multi
shot molding eliminates the labor, machinery, adhesives and mechanical
fasteners required for assembly. This simplifies production and lowers
manufacturing costs. It also improves the lot-to-lot consistency of
products. The in mold combination of two or more parts into one reduces
the amount of quality related inspection of individual components. Less
assembly and inspection translates into less component handling, which
in turn lowers the risk of contamination. Multi shot molding also can
eliminate downstream decoration operation. Text, logos and other graphic
designs can be molded into products, producing more durable decorations
than labels and stickers. The most important advantage is more
important than its effect on product quality. Though multi shot molding
can streamline the manufacturing process, reduce part costs, and improve
product quality, it is not without significant limitations.A number of
techniques are used for multi shot molding. The choice of a method is
normally based on cost and part design. Common multi shot methods
include over-molding, common core, rotary stripper plate, and core
toggle or core back.China Composite Resin - Construction Structural Adhesive for Anchoring (Bucket) ManufacturersOver-molding
involves two separate molds in two different machines. After plastic
components are molded in one machine, they are brought to a second
machine that adds a rubber layer or part to the components. A relatively
low cost two shot alternative, over-molding is suitable for low-volume
jobs that do not justify the purchase of expensive two-shot machines and
molds.In common core process, parts stay on a common core throughout
the manufacturing process. After the first shot, a platen or turntable
rotates 180 degree to move parts to different mold cavities that create
space for the second shot. When second shot material must completely
envelop the first shot, molders change both core and cavity steel for
the second shot. This can be done with a rotary stripper plate, which
lifts first-shot material off its core steel, rotates 180 degree in most
cases, and then sets the material on new core steel. New cavity steel
is also waiting at the second location. The new core and cavity create
the space for second-shot material to run in, around, and through the
first shot.Another method involves no tool opening or rotation between
the first and second shots, but slides inside the tool move to create
space for the second shot. By eliminating rotation in the mold, this
method lowers two shot costs and is unlike common core and rotary
stripper plate techniques. But not all part geometries can be produced
this way. China Carbon Laminate 50mm Width, 1.2mm Thickness ManufacturersSometimes,
however, a molder can make design changes to initially unsuitable parts
that will allow the use of core toggle.Multi shot tooling is more
complex than conventional tooling because it includes rotating platens
or other features that allow it to create multi piece parts in one mold.
Multi shot tooling can usually cost at least twice compared to the
conventional tooling. Even though multi shot molding eliminates
assembly, manufacturers may find that it is less expensive to mold two
low-cost conventional parts and assemble them using a high-speed
automated cell. With its high up-front costs,China Carbon Laminate 100mm Width, 1.2mm Thickness Manufacturers
multi shot molding is normally used in high-volume manufacturing
operations that will provide an adequate return on investment. As a
general rule, multi shot molding provides cost effectiveness when more
than half a million units are made in a year. Multi shot molding has
other limitations in addition to the higher initial cost. It requires
proper gate location and proper cavity fill. Multi shot molding requires
more maintenance compared to the conventional molding technique.
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