Flashing

[Tiderunner]

All my molds are CNC molds from the usual manufacturers, and yet on some I get a lot of flashing. What are the causes of this. I use a vise and tighten the crap out of it. I use the screws that came with the molds and add clamps. I've noted where the flashing occurs and put extra torque on the area ( this seems to help).

What causes this? Am I injecting too hot? Am I injecting too long causing heat to cause slight warping? Am I over tightening, causing uneveness? I clean my molds, stop injecting when things seem to hot.

It's only certain molds.

[Fishermanbt]

All the molds I have or have had do not need excessive clamping pressure. They just need the right amount of clamps in the right areas. Try this and see what you get.
Clamp up the mold(s) firmly but don't try squeeze them hard. Shoot your plastic at 320° then try backing the temp down 5-10°. When you find the sweet spot on the temp that the mold doesn’t flash use a sharpie marker and write that temp on the mold. Slow down your injection plunge. If it’s a mold that requires holding pressure to fill appendages or antenna back off on the holding pressure. 

[SpoonMinnow]

Does your mold have alighnment posts - not just screws that hold the parts together? I wasn't using them and had flashing. Like BT said, too fast an injection can also add to flashing. My problem though has been a bubble inside the body of some of the grubs.

[Tiderunner]

On 6/22/2023 at 2:45 AM, SpoonMinnow said:

Does your mold have alignment posts - not just screws that hold the parts together? I wasn't using them and had flashing. Like BT said, too fast an injection can also add to flashing. My problem though has been a bubble inside the body of some of the grubs.

Yup. All of my molds have these, except I have three of Do It Gary Yamamoto CNC senko mold. That one does need to be clamped. And has never given me flashing problems. 

I Have a Cut Tail worm mold where the flashing was around the tail. I tried tightening the screw that is closest to the tail, and that seemed to work.

The molds that seem to give me the most trouble have screws at the ends but nothing in the middle. One mold the screws are in the way of the vice, and the other molds. I have 4 of these, and inject all 4 with the screws out. Counter sunk screws would have fixed this instead of oval head.

I have been a busy bee pouring the past week. I have tried using less pressure. And injecting at around 300*

I still think that when injecting large amounts, the molds are getting way too hot, and warp slightly. That may be why shooting at a cooler temp has help. Less warping, and plastic not as runny. Maybe warping isn't the right word, maybe flexing? Expanding?

Maybe the manufacturers should consider a screw in the middle as well as the ends for the longer molds? That would certainly help. Molds lately are getting bigger with more cavities, and yet just still only 2 screws.

It doesn't take much to overheat aluminum

[Jig Man]

Have you considered drilling holes, threading them and adding screws?

[Apdriver]

I’ve taken all the thumb screws out of my molds and use 5 or 6 inch C clamps. Sometimes 4 inch depending on how many molds I shoot and haven’t had any troubles with flashing. The thumb screws or even the knob screws are too tedious for me. 

[Les Young]

I have the screws taken out of almost all of my molds & use the plastic squeeze clamps. I put on  as many as i can get on them on just to be safe. 

Edited June 29, 2023 by Les Young

[Tiderunner]

On 6/24/2023 at 11:56 PM, Apdriver said:

I’ve taken all the thumb screws out of my molds and use 5 or 6 inch C clamps. Sometimes 4 inch depending on how many molds I shoot and haven’t had any troubles with flashing. The thumb screws or even the knob screws are too tedious for me. 

 

On 6/28/2023 at 8:22 PM, Les Young said:

I have the screws taken out of almost all of my molds & use the plastic squeeze clamps. I put on  as many as i can get on them on just to be safe. 

This is what I do as well. I think I've beaten the flashing issue by doing these things.  Extra clamps. SHooting at lower temps. And not putting as much pressure on my injectors.
If the plastic is too hot I've been using a new tool called patience and wait a few minutes for it to cool down. And I try not to put all of my 220lbs into injecting. Baits are coming out much better.

Also after injecting for a while and molds and injector is hot to the touch, I end the session. I probably need another injector. That would help speed up production.

[Les Young]

9 hours ago, Tiderunner said:

 

Also after injecting for a while and molds and injector is hot to the touch, I end the session. I probably need another injector. That would help speed up production.

Sometimes i take my dual injector apart & use all three 6oz. injectors. I'll also put cool unused molds in between the ones i'm shooting to sort of act as a heat sync of types  if i plan on making a large amount of a couple different  baits in the same colors. Things like brush hogs & super hogs i always use the same colors in so it makes it a lot easier to make a bunch of them at once. Three different jig trailers that i use i do this way too & you can really make a pile of them quick.