Pin Point Gate Construction

pin point gate is commonly used in 3 plate mold types, see explanation more about 3 plate more here, basically the pin point gate part is like picture below
































those picture is pin point gate picture, to make gate like that we can buy pin point gate bush in mold manufacture company or we make it by EDM (electronic Discharge Machine) Process, the special EDM torch for Pin Point gate also available in mold part markets.
Pin Point gate Bush
picture below shown simple pin point gate bush,




































the construction to assembly the pin point gate bush in mold is like picture below
straight, without extended bush, picture below shown, locating ring, pin point gate bush, runner lock pin, runner, product and mold base plate (top plate, stripper plate and cavity plate)



some times, we need extended pin point gate bush, why when plastic material have high shear rate, we need to assembly extended bush, so from diameter gate until runner plastic material will easy to flow the cavity.
see the construction at picture below


here some good link of standard component of gate,
http://www.misumi-europe.com/www/lang/catmold_eng/nav/006/hl/007/menu/catalogues/fn/21/content.html

Read More

Opening Construction of 3 Plate Mold Type

previous post http://mould-technology.blogspot.com/2008/08/main-construction-pin-at-3plate-mold.html
we can see closed condition of three plate molds

picture below is shown three plate condition when open


basically there are three opening type in 3 plate molds base
1. Sprue Cut Opening
2. Runner Opening
3. Product Opening

below i try to explain in simple words
1. sprue cut opening
this opening will cut sprue from nozzle, so the feeding runner can take easily by arm robot or manually by hand, this opening use puller bolt and runner stripper plate to cut the sprue. the stripper plate will move after puller bolts pulled by cavity plate, remember that puller bolts also end mounted in cavity plate.
the opening length between 5mm until 10mm.
2. runner opening
this opening use tho open runner system, than runner will take by robot or manually,this opening will make space between stripper plate and cavity plate.
to make sure this runner opening safely, attach spring in puller bolts between stripper plate and cavity plate, or use other methods like attach spring in out of puller bolts. length of this opening is same with runner length + 20 mm.

3. product opening, as we know this opening is to open the product, make space so the product can be ejected from core.
this opening length is about length the product + length robot arm + 10 until 20 mm to make save space when product ejected.

Opening Sequence

actually to pull the cavity plate, so the cavity plate can pull the puller bolts than open the stripper plate have two types, using tension link and magnet.
OK, at this post let's learn when using tension link.
1. first Opening is Runner Opening
why ? becouse between stripper plate and cavity plate,some springs always attached at there, some mold designer attach at puller bolts, and the other attach in each side using pin and make some hole to attach the spring. but i prefer attach the spring in puller bolts, it more easy in process.(sorry at picture above i don't write some spring)
2. Second Opening is Product Opening
Parting Line between core - cavity plate always easy to open, when moving plate at the injection machine pull the bottom plate until core plate, it will make Product Opening open.
3. Sprue Cutting Opening
after moving plate pull the core plate, with tension link core plate will pull the cavity plate until cavity plate pull the puller bolt, and make some space to cut the sprue from nozzle.

Read More

Main Construction Pin at 3Plate Mold

I take those topic, to start learning about kind of pin on 3 Plate Molds, becouse between 3plate and 2 plate mold have several different function of Pin.
Basically 3 Plate mold to support the main construction have 3 kind of Pin.Look at picture below


(click the picture to enlarge)

3 Part Pin are
1. Main Support Pin
2. Positioning Pin
3. Puller Bolts

those pin will support both opening and closing process of 3 plate type of injection Mold. the function each pin are

Main Support Pin
this pin is totally support cavity, and runner plate when molds in open,when we buy mold base plate from fabricator, they always have exact diameter of Support Pin that we needed, it was calculated, but if your part is precision ensure it by calculating the deflection of those pin caused by cavity plate and runner plate.
make sure the deflection of pin not larger than 0.1 mm, choose more large diameter of Support pin when deflection is large.

Positioning Pin
Because support pin doesn't precision when closing, we need more precision guide part, this part also named Guide Pin, becouse it will guide core and cavity matching together. use this part with the Bush, in high precision part, some times we need more than one Positioning Pin, we can also add block guide, taper block set, taper pin set and other high precision positioning tools.

Puller Bolts
puller bolts doesn't support any plate, this part actually include in opening part of three plate molds.
working together with tension link or magnet block, this part will make parting line at stripper plate and top plate, this parting line used to make sure that sprue was cut from nozzle.

Parting line Opening is about 5-10 mm, depend on large of molds.

look at picture below to learn the length of each Pin.

Read More