Top Plate, Stripper Plate,Sprue Bush and Runner Lock Pin Design

at the picture below you will see a set of Top plate until stripper plate design related with runner flow, at this picture support pin exclude. the mold type in this picture is 3 plate type.

the runner system accommodates the molten plastic material that coming from barrel, and guide it into mold cavity, the dimension, configuration, shape, and system connection with mold cavity will affect filling process.



as see from that picture, red plate indicate isolated plate, it's doesn't matter you use isolated plate or not, but you must see more in injection machine, if it needed isolated plate give it. number 1 and 2 in black plate it's indicated top plate for number 1 and stripper plate for number 2, those picture shown 3 open mold type.
after injection, in ejection process stripper plate will open because puller bolt pull it( not include at those picture).

runner ejector set will needed to push runner, after ejection, but if you use arm robot or manual take the runner by hand operator it doesn't needed. runner ejector set always contains spring, those spring will push pin in ejector set and will push the runner.

runner lock pin function is to pull runner when ejection begin still in top plate, if runner adhere in stripper plate, the robots or operator will difficult to take the runner, because no ejection system for runner in stripper plate.

when design the runner system and ejection system for runner in 3 plate type of mold you should use those mold accessories.

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Types of Runner depending temperature

there are various concept and type of runner, here we will give explain about runner type depending on the temperature control, we could divide in 3 type :
1. Standard runner system
2. Cold runner system
3. Hot runner system

standard runner system are directly machined into the mold plates (plates 2 or plate 3) but we can also make in special plate that called runner plate, this plate usually use in 3 plate mold type and attached in plate three(cavity plate)
at this picture below shown that runner directly machined in plate three


but picture below shown special plate called runner plate, those runner plate will attached in plate three, you can see from this plate that mold will have 4 cavity od product.


Cold runner system
this runner system have similar use with hot runner, but in different temperature, the temperature between 80-120 C, this Cold runner system used in reactive material such us rubber and thermosets type of plastic.
the difficulties in Cold runner system is
- high pressure consumption, so design more expensive
- because material is reactive, a little different temperature make different viscosities, this will make every cavity have different time to full fill.

Hot Runner System
this system should be viewed as extended nozzle in form of block, the hot runner system contains : sprue bush, runners, gate and extended nozzle, the advantage of hot runner is
- they can completely eliminate runner scrap, so there are no runners to sort from the parts,
- no runners to throw away or regrind and remix into the original material.
- no loss of melt and thus less energy and work input
- easier for fully automatic operation
- very good quality because melt can be transfered into the cavity at the optimum site

the disadvantages are :
- high cost
- thermal isolation from the hot runner manifold block is problematic

Hot runners are popular in high production parts, especially with a lot of cavities

there is 3 type of Hot Runner are :
1. the insulated hot runner,
Insulated runner molds have oversized passages formed in the mold plate
Heated type Hot runner
2. the internally heated hot-runner system,
3. the externally heated hot-runner system
internally heated and externally heated. The first is characterized by internally heated, with the heat being furnished by a probe and torpedo located in the passages. This system takes advantage of the insulating effect of the plastic melt to reduce heat transfer (loss) to the rest of the mold. The second consists of a cartridge-heated manifold with interior flow passages, look at picture below to learn more

this picture take from http://www.scudc.scu.edu

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When we need slider parts in Mold Design

second previous post i have post about the slider parts and construction in complete mold base , then now i give a little brief when we need slider in mold design, basically we design mold from our customer, first is we must look the parts that we will make by plastic mold, look mare at the drawing so we can know about tolerance and critical point of parts, seconds is define the parting line, first parting line is between core and cavity parts, and after that if the parts have side form we must define slider parting line, look picture below



from those parts we know that we need slider parts, side hole and other shape that can not form by core and cavity became slider parts. below is picture in 3D modeling,look at the hole shape in side, those shape need slider part.



and how the construction of slider, more about construction mold you can see by clicking mold construction or molds parts in quick topic, basically here i give slider 3D modeling and parts name, those parts names i take from Misumi standard mold design


you can use this tutorial for education and others purpose but still write copyright from this site.

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Mold Handling Picture after Assembly

Picture below show 3 plate mold after assembly, the position indicate ready to handling by crane, eye bolt was attached at center of mold plate.

after assembly process, make sure you has attached the tension link in 3 plate mold type or safety bolt or magnet in 2 plate type of mold this to prevent mold plate falling down when handling up with crane, when design eye bolt for handling, give bolt hole about 1 cm more to cavity direction from center line of mass of mold, it's commonly in plate 3 or 4 depending on how wide each mold plate, why it's must move about 1 cm ? the reason is same as safety bold, by move those bolt position when handling with crane mold base will decline about 5-30 degree, and top plate in upper position, this method make more secure when handling.

at this picture below, number 1 is eye bolt position in ready position to handling, and tension link (2) was attached.



from where we know that those mold is three plate, from the characteristics of three PLATE MOLD we can see from picture that :
1. Attached tension link, tension link function is o pull plate number 3 or cavity plate then by puller bolt, cavity plate will also pull the second plate, and cut the runner from nozzle.
2. second plate, it's indicate that those mold is 3 plate mold type, why because in 2 plate type, second plate is doesn't use. second plate is necessary when gate type is pin point gate.
3. runner plate, if you see more carefully, between second plate and third plate attached runner plate, in 2 plate mold type, runner plate does not use, because runner attached in third plate.

green arrow show injection nozzle machine where must be attached and indicate flow of plastic material during injection process.

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Slider Design and Basic Construction

picture below show slider basic construction in Mold, various construction and litle part available in slider but the basic construction of slider is same, look picture below, sorry if this picture is too grainy, i'll make a new one.


the main part from those picture is mold plate, number 1 until 10 is shown the plate of mold
plate 1 is top plate
plate 2 is gate opener plate, retainer plate, and others name depend in fabrics
plate 3 is cavity plate
plate 4 is core plate
plate 5 is backing plate
plate 6 is support plate
plate 7 is ejector plate
plate 8 is ejector retainer plate
plate 9 is bottom plate
plate 10 is runner plate

and the slider part name are
g for angular pin, this pin always have certain degree, usually between 10-30, angular pin will transfer vertical movement to horizontal movement, others construction, angular pin not from the top but from bottom, this kind of construction is rare to use now.
h is slider core, when contact with angular pin, this part also the core from slider construction, at this part we can attach insert part that mold the shape of plastic.
i is slider locking block, we can depend in angular pin when mold closed, slider pin is too week, so the holder of pressure from inside mold during injection process is locking block.
k is slider lock plate, for non mass production you do not have to attach this part, but if the mold used in mass production, i suggest to use this part, because slider locking block and slider core always have friction, then when this part broken or got abrasive is will need expensive cost to repair it, so use lock plate is better, is cheaper.
l(L) is slider insert, this part which form the plastic product, it's attach in slider core

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