Tips on Injection molding machine nozzles.

When using an injection molding machine, then you have to be careful in picking out the ideal injection molding machine nozzle for your mold. It should be a clean nozzle that allows the material to flow and pressurise the mold needed. This usually means you should avoid using obsolete or worn-out nozzles for injection molding machine work. It might cause a nozzle leak.

injection molding machine nozzle problems

A poor fitting of the machine nozzle can cause you a lot of problems during injection molding. If the nozzle is not centered correctly against the back of the mold, the nozzle can leak. This can cause a big mess that can put your machine down for days and cost hundreds of euro on replacing heater bands and thermo couples. So away worth check nozzle center regularly. Also if possible at the start up of production to use a bit or cardboard between the nozzle and the sprue bush , to check alignment.

Also remember it may not be you nozzle alignment issue it coule be the sprue bush centering. However start by checking the nozzle alignment.


injection molding machine nozzle size

The nozzle radius should be smaller than the sprue bush radius, so that the seal off is strong. The Sprue bush nozzle radius usually comes in 1/2 or 3/4 oe 1 inch sizes. Also the nozzle opening should be slightly smaller than the sprue bush opening.

If I could give you just one piece of advice that is try standardize your nozzle size in your factory as much as possible, this will save you a lot of hassle. By having standard nozzle sizes and corresponding sprue bush sides in your molds then you do not have to worry about mis-matching issue.


injection molding machine nozzle types

There are 3 main types of nozzles. The general purpose is the most common any usually comes with the machine. However these can have dead spot in them, that material can degrade in. Causing intermittent black spects in your parts. The reverse taper nozzle may give less pressure drop but more lightly to drool. The Free Flow nozzle would potentially give less pressure drop and a cleaner break away. Depending how you want the sprue to break away when the mold is opened and if pressure drop is critical for your mould.

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injection molding machine nozzle filter

A nozzle filter inside your nozzle can help catch any contamination in your melt. If it is critical that you do not have any contaminants in your parts then placing a filter inside the nozzle is whats needed. However you should know, this will increase the pressure drop across your nozzle, so be careful if you are running your machine near its pressure limit. You should also know the filter will have to be removed regularly for cleaning and inspection. You can monitor this on your machine to note any increase to injection pressure over time. If regulare color and material changes are needed then the filter nozzle may need to be changed each time. The filters come with different mesh sizes depending on the size of contaminates you want to catch. However the small teh filter size the more pressure drop there will be.

Custom nozzles with filters
Custom nozzles with filters

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injection molding machine nozzle tip material

Most standard of the shelf nozzle you buy are made from a hardened steel. You can get custom nozzles where all dimensions can be customized for your machine and mold combination. You can also specify the type of material you wan the nozzle made from. These nozzle are not expensive and give you the flexibility to set your own standard. Below is the type of information you would need to supply to get a custom nozzle.

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injection molding machine shut-off nozzle

There are many different types of shut off nozzles however the most common would be the mechanical and spring shut off types. These shut off nozzles are commonly use to eliminate nozzle drool. However I would suggest reducing nozzle temperature, contact time with the mold and nozzle length so as to eliminate nozzle drool. However some material can have very low melt viscosity or the cycle times are so quick that a shut off nozzle is the only option. Just be aware of possible dead spots in the nozzle design as well as regulare cleaning and maintanence will be required. Also if regulare color changes are needed then this may take longer.

Mechanical actuated shut off nozzle
Spring shut off nozzle

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How to change your injection molding machine nozzle

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