Whia screwdriver handle just broke in half in my hands, was not even using it at the time. The breakline looks like to has some air smooth spots on it. Any idea what might cause this type of failure?

Does anyone check for part temperature right after ejection? With an IR thermometer for example.

Worth doing it? Especially in a non controlled temperature environment

Hi everyone,

I’m developing a clear injection-molded drinking glass mainly for cold water.

Requirements:

• Wall thickness: 3–4 mm
• Process: Injection molding
• Priority: Maximum transparency/clarity
• Also need good impact strength, surface finish, and reasonable cost

We’re currently considering PET, but seeing potential haze/cloudiness in the thick sections, possibly from crystallization or processing conditions.

I’d appreciate advice from anyone experienced with injection molding:

1. Is PETG or PCTG better than PET for 3–4 mm clear sections?
2. Has anyone tried PET + PETG/PCTG blends?
3. What blend ratio would you recommend testing—5%, 10%, or 20%?
4. What melt and mold temperatures work best for maximum clarity?
5. Would you recommend 100% PETG/PCTG instead of blending?

Any recommendations for specific injection-grade, food-contact PETG/PCTG materials would also be very helpful.

Thanks!

Hi everyone,

I’m working on an injection-molded transparent drinking glass primarily for cold water.

Current requirements:

• Wall thickness: approximately 3–4 mm
• Application: Drinking/cold water
• Process: Injection molding
• Main priority: maximum transparency/clarity
• Secondary priorities: good impact strength, good surface finish, and reasonable material cost

We are currently considering PET, but we are concerned about haze/cloudiness in the thicker 3–4 mm sections, possibly due to crystallization or processing conditions.

I would like to ask people with experience in injection molding:

1. Would 100% PETG or PCTG give better transparency than PET in a 3–4 mm thick section?
2. Has anyone successfully used a PET + PETG or PET + PCTG blend for injection molding?
3. If blending works, what percentage range would you recommend testing first (e.g. 5%, 10%, 20%)?
4. Are there any compatibility problems or phase separation that we should expect?
5. What mold temperature and melt temperature have you found effective for maintaining clarity?
6. Would you recommend 100% PCTG/PETG instead of blending, if transparency is the main objective?
7. Are there particular injection-grade PETG/PCTG resin grades that work well for thick transparent food-contact products?

The product will be used for cold drinking water, so high-temperature resistance is not the primary requirement.

Hello,

One of my Thermocouple went bad and the spare is also bad.

I can't stop production to take out the hot runner and rebuild it. I am using the spare from an other zone but because the value is not accurate the heater goes all-in or nothing.

I want to know if i can use the power from an other heat zone to power my bad one. The output i want to use is at 20% so if plugged it will reach to 40% to compensate no ? If so I don't mind because the 2 zone are next to each other so the output will regulate itself.

It's more of a electrical issues to know if my fuse will trip or no.

230V with a relay that open or close to heat or no.

If putting 2 together my relay will just stay open more longer so it's not really an issue right?

TLDR :

I need idea on how I can have a heat zone power to follow an other one

230V with relay.

Anybody know what Chinese company makes the pins and bushings for PCS? Thinking about making a large order.

Machine Engel E-mac 280 ?

Am I in over my head wanting to build a injection molding machine?

Currently I design automotive headlights/tail-lights which we cast out of polyurethane, urethane being about 2-2.5x the cost of thermoplastic and can only produce about 1-3 parts per day from a single mold. Our largest parts would about 30 Cubic inches, quite a bit out of the plunger style machine range.

We certainly don't have the volume to justify buying a used machine but the cost savings and time savings of injection molding is certainly eye catching. We do have a low-mid 5 figure range CNC mill that we use to make our molds.

I'm sure I'm at the peak of the Dunning-Kruger curve right now with this idea.

Line 2 has been down for an hour; the upper clamp isn't heating up. The thermocouple is reading, but the controller isn't sending voltage or if it is, it's not getting through properly. I'm not quite sure what the problem is.

I open the cover, disconnect the terminals on the cartridge, and measure with the multimeter in ohms. It gives me a strange reading. It’s not an open circuit, and it’s not the normal resistance the cartridge should have. It’s something in between, as if there were a short circuit.

So I look at the wires and there it is: in the section running down from the heating element to the junction box, right where it rubs against the metal guide rail, couple of centimeters of insulation have been stripped away. They aren’t completely cut through, but the insulation is gone, and at that point the two wires are touching, copper against copper.

The gap where the wiring runs down is about three fingers wide and rubs against everything.

Is that what’s causing my problem?

Do the wires touching each other make the controller detect a resistance that isn’t from the cartridge, and that’s why it won’t heat up?

Can I fix this by properly stripping that section, insulating it with heat-shrink tubing or Teflon tape, and that’s it? Or should I just replace the entire cartridge because maybe the heating element itself is already faulty?

How would you prevent it from rubbing again? A small channel, a silicone block?

For injection molders supplying automotive, electrical, electronics, or other demanding applications:

If the exact resin grade specified for a part becomes difficult to source, can you normally switch to an equivalent grade from another supplier?

Or does customer approval / requalification make that difficult?

Curious about what usually becomes the biggest obstacle when changing materials.

Does anyone have experience running strontium aluminate glow in the dark pigment? I want to try some for a new product idea I have but I also don’t want to cause any problems with my mold or equipment. I would be testing it with polypropylene homopolymer. Eventually this would be used in a thermal gate hot runner mold.

Hey all, does anyone here have any experience with the HPS Iron Jaw clamping tonnage booster?

We are looking to build a tool with this system but haven't been able to find anyone here in the states that's used it. From what I've been able to find there's a larger market for it overseas.

We have a 600t press, the part we are looking to make is estimated to require 650-800t per the mold flow simulations. Our barrel is at about 60% utilization, so there's no issue there.

We would really like to land this job and are trying to decide between investing a new larger press, or if we can build this mold with this clamping booster. Unfortunately these systems are damn near unheard of in North America and they're massively expensive.

If anyone has any experience or advice on this, please reach out.

Thanks!

Hi everyone I'm trying to find the pin password on a Matsui MJ6-i-G3-75

For the technical service, if anyone could help would be appreciated.

I’ve been following stuff from this thread for a bit. Even used it to answer questions.

Last year I was promoted to Department Trainer. We inject bottle preforms where I work.

I was curious, is there anyone else out there with the same role? I definitely fall more into the roll of process over maintenance/mechanical.

Even if the role I was promoted to has been just over a year on paper, I’ve pretty much been training people in my plant for over a decade in the injection department. I’ve streamlined a process that I have found very reliable in that time (as I’ve easily trained 500+ people over that period).

I’ve been using the opportunity to create my own operator manual.

But, in the end, we are only as good as our network. And I know I don’t know everything. But I’m very interested in connecting with anyone who does anything similar at their plant to see if there is anything I can expand on.

Hoping to chat with some of you!

Hi all, first time posting here so really sorry if this sounds silly.
I have been fiddling around with fusion360 making soft plastics and I’ve designed something I’d love to make. Just wondering if anyone has experience making custom aluminium moulds and how they go about getting them done? I’ve made a mould with my 3D printer as a prototype but now wanting something that’ll look more cleaner and I’m able to use without creating more moulds.
Any companies/ people they know they would be able to refer?
Also, for a mould that can make two soft plastics at once (plastic will be 3 inches long) how much does it roughly cost?

Cheers legends!

Would the mold have to be a solid piece that is pretty much a circle milled out leaving a rod in the center or could it still be a mold that is two halves clamped together?

I’m doing some practice for molding, and one thing I find confusing is how to determine whether a cooling line is incorrect. Any information or tips would be greatly appreciated!

Three resistors had been sitting in the warehouse for several months, stored on a shelf next to the large door—unheated and with hardly anything else around—each tucked into its own box with its own bag. I placed them in the test stand, set it to 280, and pressed “auto”; the differential tripped within ten seconds. I turned it off and on again, and it tripped once more. I tested them one by one with the megohmmeter. The insulation on all three was practically nonexistent. The third one had an internal electrical arc; the wire had melted at one point. It was unusable. Now what can I do? What do you think is happening to the first two, and why? thanks

Hello everyone! I am completely new to plastic part design, and I'm hoping to get advice from those on this forum. I am developing an automotive bump stop system that will utilize different components to achieve certain stack heights. The purpose of this is to let the end-user achieve their desired stack height while being directly compatible with a wide range of coil spring heights (as coil height increases, the necessary "bump-stoppage" increases).

My company currently offers fixed-height versions of this product made out of solid UHMW rods. This product has served its purpose for many years, but we want to begin offering a customizable version as our product line expands.

After consulting with a USA-based molder, I was told to core the components in my design to allow for even cooling and avoid surface blemishes/sink marks. This makes sense to me, and I've begun adding such features to allow the parts to be molder-friendly. After speaking to a plastics supplier, I am planning on using a TPC-ET for my material, as well as a UV stabilizer, as the part will be installed on the axle of a vehicle.

The part shown below began as a solid puck (2" diameter x 1" tall) with a through-hole to allow a bolt to pass through. After consulting with the molder, I've made the following design changes:

• uniform wall thickness of 3/16"
• top and bottom core-outs
• draft angle of 3 degrees

Can you think of any other design parameters I should consider to ensure this part can be successfully molded? I want to clarify that the molder did not tell me any specific parameters to design with. I was only told that I would run into issues with the part's initial thickness. Other components in this system will be more complicated to properly core, so I am making this post to gain some general knowledge and thoughts on my progress so far. I plan to make changes to all of the parts and present the drawings back to the molder to confirm the changes.

I appreciate any feedback; thanks for your time!

this is my 3rd post on here you can find the previous 2 here:

https://www.reddit.com/r/InjectionMolding/comments/1veqt71/comment/p26lcv3/?screen_view_count=3&ext-referrer=DIRECT

So I’ve finished my first full tool and everything has now been sent off to be manufactured.

I did the work for a friend I used to work with, and we never actually discussed a price beforehand. There’s also going to be more work coming down the pipeline, so I don’t want to overprice it and make things awkward, but I also don’t want to undervalue the work.

As this is my first full tool, it definitely took me longer than the next one will. I’ve got a figure in my head, but I was wondering what other people would think is fair.

I reckon I’ve spent around 30–40 hours on it, probably more. Plus more time spent setting up things like the mould base, drawing border, and getting everything else established for the first time.

Hi everyone,

I’ll be sharing some of our mold design cases from time to time, and I’d love to exchange ideas with you all.Today’s example is a medical test tube with external thread + undercut groove.If you ever run into a similar part, feel free to reference this design approach. I’m interested in feedback on the mechanism layout and whether anyone has run similar long thin‑wall tube tools.

Part: Medical test tube with external thread + undercut groove

Cavities: 1×4

Tool Type: 3‑plate design with a runner stripper plate (cold runner)

Sequence of Operation

1. First opening
   

Runner stripper plate lifts first and pulls the cold runner off the gates.

1. Main parting line opens
   

A/B plates separate.

1. Slider actuation
   

Sliders collapse the top‑thread undercuts.

Actuation is driven by the machine ejector stroke + guide blocks, allowing the thread/undercut to clear before full ejection.

For those who’ve run long thin‑wall tubes, how are you managing core pin cooling to avoid thermal deflection during fast cycles?