Shop Floor Talk  

Go Back   Shop Floor Talk > Welding and Metalworking Forums > Fabrication

SFT Search:   
Reply
 
Thread Tools Display Modes
  #1  
Old 10-15-2013, 10:00 AM
dubby's Avatar
dubby dubby is offline
Twice the size--half the man
 
Join Date: Apr 2006
Location: Lubbock, TX
Posts: 10,030
Default Heating elements and control systems

In our plastic lure making setups, we commonly use a pot manufactured by Presto for kitchen use. It's basically just a fry-daddy with a selectable temp control. Users heat their raw plastic in it, add colorant, and then draw the plastic out with an injector to shoot into their molds. Requirements are pretty basic...get to temp, hold temp, and keep cycling as needed. Temps vary between 290-370° depending on type, but it stays about 320° normally.

Another product we have, is a heated block that draws from a tapped hole in the bottom of the pot. It has a built in mechanism that acts as a valve to start/stop plastic flow into the injectors. It uses the 1/4" cartridge heaters and a controller. I have only seen pictures of it, never used one of these, as it's made by an outside fella and I really have no need to spend the money (even at cost) to have one in my shop here. Video here.

The weak link in the system is the actual injector itself. I've been making the standard hand injectors, and I've taken a couple of the ones like in the video in for tuning to fix little issues the customers have had. The biggest problem with the ones that are being made now is that no two are ever alike. The machinist making them builds them to work, but when they break, the whole thing has to be sent in for repair/replacement because you can't just send out a part. You just don't know if it'll fit or not.

I understand all the mechanical parts of it, that's really simple. What I don't know about are the electrical parts. What type of heaters to use? What type of controller? What else do I need, or how could I make it better?
__________________
I've always had more time than money.

Wade's Custom Kydex
Reply With Quote
  #2  
Old 10-15-2013, 05:36 PM
Scotts's Avatar
Scotts Scotts is offline
Stuff, Just stuff
 
Join Date: Dec 2004
Location: Wichita Kansas
Posts: 5,529
Default

Dubby,

you will need the heaters, look for voltage and wattage size you want. you will need a controller and contactor. as the heater will probably pull more amps then the relay in the temp controller will handle. You will need a thermocouple to measure the temp of your media, for those temps a type J should do you fine.

You are talking about the little silver box on the left side of the left pot in the video?

That has all that in it. Controller, thermocouple and contactor.

Go here and look around, you can get the $300 temp controllers for $100 bucks or so from Here, also look for the contactors from factorymation as well.

IMS has fairly good prices on heaters. usually cartridge heaters have all the info on them stamped on the outside. If you know someone with the setup you can get them to pull or ohm out a heater and find out what they have.

We should be able to get you up and going without too much pain and suffering.

You may be able to get some of this stuff down at the salvage yard.

Scott
Reply With Quote
  #3  
Old 10-15-2013, 08:18 PM
GWIZ's Avatar
GWIZ GWIZ is offline
SFT Historian
 
Join Date: Feb 2006
Location: USA
Posts: 7,436
Default

From inside this link.
http://www.shopfloortalk.com/forums/...ad.php?t=16017


Found this,
You will have to match the type of probe to the controller this link shows type K
http://www.auberins.com/index.php?ma...dex&cPath=20_3


I don't have a clue on heaters because my soldering irons range 25 watts to 600 watts or so, more then likely will have something to do with the amount of surface area you want to heat and time to get up to temp.


Maybe a cheap way is to use a HF router speed controller and mark the knob with a temp range.
For safety mount a 400 deg over temperature switch with relay to kill the power.
__________________
*
*
The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment. ~Warren G. Bennis
Reply With Quote
  #4  
Old 10-15-2013, 08:49 PM
BukitCase BukitCase is offline
Elite Member
 
Join Date: Feb 2013
Location: Lost in Oregon
Posts: 1,245
Default

If you were closer to the gulf I'd try to steer you AWAY from a type J thermocouple - all tc's are created by welding two dissimilar metals together - as the temp changes at that junction, they generate a varying millivolt signal across the junction, which is used as an input to a controller or indicator, or both.

The two metals used in a type J are Iron and "Constantan" alloy - the iron doesn't do well in high humidity, connections tend to rust up pretty quickly unless they are hermetically sealed.

Type K's use "Chromel" (NiChrome wire) and "Alumel", another alloy. Neither side of a type K is prone to rust/corrosion - they will typically stay good for 10 to 50 times as long as a type J, especially in high humidity conditions.

Instrumentation in this century is plenty accurate at lower temps with a type K - Old fossil-type instruments not so much, which is why the "Lore" still says use a type J for lower temps.

K's these days, with fairly new instruments, can handle anything from your refrigerator to your forge - makes it simpler to rig up something like you're wanting to do... Steve
Reply With Quote
  #5  
Old 10-15-2013, 09:46 PM
coleasterling coleasterling is offline
Senior Member
 
Join Date: Jun 2007
Location: Post and College Station, Tx
Posts: 536
Default

I've never used either of these, but for the price they seem worth messing with.

http://www.amazon.com/AGPtek®-K-Type...ure+controller

http://www.amazon.com/Digital-Displa...MHEPZ3RS18JWZM

-Cole
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Web Search:

All times are GMT -5. The time now is 04:29 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.