Tab gate design in Mold

general construction of tab can see at picture below


basically melted material is fed to this gate from a separate primary gate (after runner), the function of the gate typically is employed for flat and thin parts to reduce the shear stress in the cavity, Tab gate able to used in various material plastic such us ABS, PS, acrylic, PP, PVC, Polycarbonate. SAN and other which has relatively low fluidity. at this type of gate, the high shear stress generated around the gate that trimmed after molded. this gate sometimes also called the collision gate.

Function in Product and General Rule
The thickness of tab gate should be the same as the part wall, yo can also make more thin, but when designed parts for cosmetic parts if preferred that the thickness is same with the product thickness.
rule number two is, make the gate as center as possible in the product side, but you must consider the product size and shape.
basically minimum tab width is about 6,5 mm and the tab thickness minimum is 75 % from the thickness product


for more picture and drawing view,please look at picture below

(Top View of Tab Gate)






(Front view of Tab Gate)





(Side View of Tab Gate)

each picture is able to enlarge by clicking the picture.

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side gate, edge dimension design

edge gate is the simplest type of gate and is used wherever the product can or must be gated from parting line. it's designed commonly for injection machine attended by operator, because the product must separated from the runner system by hand with the aid of side cutter.

Dimension
Picture below shown ideal configuration and practical gate, suggested dimension for general application of edge or side gate are


Runner width and Height for side gate or edge gate is preferred that height is about 0,7-0,8 from width of runner. the width of runner very depending on product size and weight, it from 3 mm until 7 mm in width ( product mass until 200 gram in maximum).
Gate width and height is about W=3h,with W is width and h is height (look at Herbert Rees, Mold Engineering, pg 159) but this rule can't applied for all part or product form, specially for thick product that have large in width such us panel and cover, when design the dimension of gate take the rule that height of gate is must about 75 % from the parts thickness, Suggested take 0,6 until 0, 7 from parts thickness, but specially for elastomer material take more large about 80-90 % from parts thickness.
T is gate width, for product mass until 200 gr, suggested take 1 until 5 mm in width , for the very large product some times have width until 12 mm.
C is Land of gate from runner, the length is should be no more than 1,5 mm. also preferred make taper before gate land, in that picture taper are change with R in both side, make R, taper or not is depend on side gate size and form.


Picture 1.A

Picture 1.B

both those picture shown edge gate or side gate with different design, application, parting line, taper and R system. taper from bottom runner to gate land have various dimension, the taper in picture 1A is enough large, about 30-45 degree, in picture 1B taper is about 10-20 degree.

beside those type of side gate, they are still various type of side gate or edge gate, will upload in other post.

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Side gate, edge gate design

as we know Gate In injection molding, is the channel through which the molten resin flows from the runner into the cavity. Generally, it is small and solidifies first. The restricted opening through which the plastic enters the mold cavity.

Standard Gate
this type of gate have various name, the common name are standard gate, edge gate and side gate, this is the most typical gate in molds, which is applied to almost all types of plastics. look at picture below, it's single side gate from sprue until gate and product (click the picture to enlarge)



how about the parting line?
the are about 3 methods that we can choose when design parting line,
1. core side process,this type of parting line only core side that's must be machined , picture below shown side gate design with flat parting line in core side process.
this type parting line is useful applied in product without taper in side of product, but when product have taper in side (like picture below) it will undercut and need slider to form the side of product.

2. cavity side process, this type of gate design parting line is one method to hide the marks of gate after injection process. at this type runner channel machined in cavity side, then a little gate machined at core side. this type of gate parting line is more good and more cheap than number one when product have taper like picture below.

3. cavity and core side parting line, this type parting line for gate and runner is not common to use, when use this type parting line runner and gate, you must use cylindrical type of runner of semi cylindrical type of runner.

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