Looking for 3mm Teflon Coated Stainless Wire

Looking for 3mm Teflon Coated Stainless Wire as a core for a mold I am designing.

I checked McMaster and they topped out at 0.082 in. I'm looking for .118in (3mm). Some of the lab and medical supplies go to .090 in, but that's still too small. Suggestions?

************* So far the best appearing solution is to get 3mm OD (2mm ID) tube and push some 2mm wire thru it. If its tight, great. I can make a jig to hold the tube straight during the process.

Looking for 3mm Teflon Coated Stainless Wire as a core for a mold I am designing.

I checked McMaster and they topped out at 0.082 in. I'm looking for .118in (3mm). Some of the lab and medical supplies go to .090 in, but that's still too small. Suggestions?

************* So far the best appearing solution is to get 3mm OD (2mm ID) tube and push some 2mm wire thru it. If its tight, great. I can make a jig to hold the tube straight during the process. =========================================================

So you need the overall od to be 3 mm, not 3 mm rod plus a teflon coating? You don't say how long or how many, but if you need a tight grip between teflon and SS you could use teflon heat shrink on SS rod, instead of pushing on teflon tubing. If the length is short, shrink in batches in an oven.

Looking for 3mm Teflon Coated Stainless Wire as a core for a mold I am designing.

I checked McMaster and they topped out at 0.082 in. I'm looking for .118in (3mm). Some of the lab and medical supplies go to .090 in, but that's still too small. Suggestions?

************* So far the best appearing solution is to get 3mm OD (2mm ID) tube and push some 2mm wire thru it. If its tight, great. I can make a jig to hold the tube straight during the process. =========================================================

So you need the overall od to be 3 mm, not 3 mm rod plus a teflon coating? You don't say how long or how many, but if you need a tight grip between teflon and SS you could use teflon heat shrink on SS rod, instead of pushing on teflon tubing. If the length is short, shrink in batches in an oven.

**************

Yes 3mm net OD. It could vary a couple thousandths. I had considered bending the assembly outside of the critical area to keep them together. Maybe even use a crimp sleeve past the bend as I know how slippery teflon is. For this application a net length of around 3 inches and about 20 pieces, but if I can make it work I would likely repeat this process for other applications. The teflon is used as it does not wick heat away as quickly as steel, the wire is because it needs to be fairly straight. 3mm is the spec.

I've done similar core pins with 1/4 teflon rod and a 6/32 machine screw threaded inside. It works. The casting fills, and the screw provides both rigidity to the pin, and a place to pull with pliers from the casting. Sometimes I can get away with stainless wire for pins, but when the clearance between the core pin and the wall of the cavity gets to small the heat sink ability of the wire/core is significant. Also, the teflon pulls from the casting much easier than a steel or stainless steel pin. You can coat steel pins with motor oil (it can take the heat) as a release, but it leaves a residue that can make succeeding processes more difficult or require a cleaning process. Graphite and talcum powder also work, but each has its limitations.

Probably your best bet is drawing a PTFE tube over a wire (and if you can draw the wire thin on one end, that'd help). It is possible, also, to get thermocouple wire in alloys like iron or chromel, with a variety of insulations (and mineral-insulated or Teflon are not unheard-of). Whether you can actually FIND a supplier of the raw wire with suitable insulation, will be a problem. In the old days, the Omega catalog would have such things, but that's changed (or my Google-fu is weak).

If you anneal, and take a few wraps around a fixed capstan, you should be able to gat a Vise-grip and comealong on the tip and stretch your stainless wire significantly to make a narrow lead section.