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Up Topic Welding Industry / General Welding Discussion / Pre-Heat
- - By Jarhead1 (**) Date 01-07-2020 20:03
Gents/Ladies -

Looking to put some parts on a weld robot. 
I have a family of parts approx sizes 4" wide by .75 thk X 12"-24" long. Material = 4140. Need to weld a 3.00" Dia X .25 thk disc to one surface 3/16 fillet all around. (Currently this is a manual weld process) This disc is just a wear pad.
Robot Cycle Time for 10 parts = approx 6 min.
My dilemma is preheating multiple parts to 500°F (the qtys are not high enough to invest in induction heating) What I'm looking for is a furnace that I can prehaet enough parts to keep production flowing. Preferably propane or equivlant. Don't have natural gas in that area.

The round disc that we are welding on is jst a wear plate.

Any recommendations is appreciated.

-Thank you
Parent - - By TimGary (****) Date 01-07-2020 21:07
This is probably not the answer you want but...

PQR + Preheat + High Strength Filler Metal + Welding Robot + Insulate and slow cool + Distortion + hoping it doesn't crack, seems like an expensive and troublesome process just to attach a small wear plate.

Sometimes the best weld is no weld at all.

Consider a single counter sunk fastener and some good 3M epoxy.
The fastener is just to locate and hold the wear plate in place while the epoxy cures.
No weld, no robot, no fixture, no distortion, no cracking potential...

Tim
Parent - By Jarhead1 (**) Date 01-07-2020 21:47
Hey Tim,

Ha would be a nice option.

We have been making these parts for decades (railcar). Unfortunately, no weld is not an option.

Our robot cell is sitting idle drooling to weld these parts and increase the throughput and Not compromising the process.

-Thanks
- - By 803056 (*****) Date 01-08-2020 15:38
There are a lot of unknowns to permit a reasonable response, but what the heck; how about a propane fired tunnel? Are you feeding the parts to the robot using a conveyor? If so, feed the conveyor through the tunnel to heat the parts to the appropriate temperature. The travel speed through the tunnel will determine how many BTUs are needed to heat the parts in the time needed to traverse through the tunnel and the length of the tunnel.

Al
Parent - - By Jarhead1 (**) Date 01-08-2020 18:46
Al,

Parts will not be on a conveyor. They will be removed from a preheat source manually and put on a fixture table on the robot.
Our robot has an indexing table> as an example Side A is welding,  were unloading/loading parts on Side B. Currently our manual process has a make-shift (natural gas) fired oven that will hold 4 parts. I like the funnel idea I was actually thinking of something on a larger scale than we are using now. I seen this as well https://belchfire.com/.
Unfortunately, we have no natural gas drops on the other side of the plant where the robot sits.
I thought some of the guys in the field would chime in since there preheating pipe, etc without natural gas.
GMAW
Lincoln LA-90 Wire

The powers to be hate seeing a robot sitting idle...

Appreciate your help..
Parent - - By 803056 (*****) Date 01-08-2020 21:25 Edited 01-10-2020 15:25
The BTUs required to heat the parts in a timely fashion may not need to be that great if there is several minutes between welding and loading. A naturally aspirated propane burner or two may be all that's needed. I'm thinking along the lines of the burners one would find in a gas grill or kitchen stove.

The Belchfire burners can really pump out the BTUs and may heat the parts up much hotter than needed for your application. I've used them on several repairs on casting 10-inches thick and thicker where the high BTUs were needed due to the mass being heated.

Your maintenance department can probably piece something together pretty easily with some refractory and ingenuity. I’m thinking of a carousel that holds several pieces on a “lazy Susan” that can be rotated by hand by the person loading the parts into the welding fixtures. The hot section can be toward the back side so the loading and unloading is performed in the cooler section.

If you really don't like the idea of a gas burner, you could consider electric heaters much like those used in an electric range. The carousel approach could again be used. There would not be the fire or flame, which would eliminate most of the fun.

The  carousel could be positioned in the horizontal position if floor space is available or in the vertical if floor space is at a premium.

Al
Parent - - By Lawrence (*****) Date 01-10-2020 13:10
If it's "just' a wear pad..

Why not consider a base metal option that has some of the qualities of 4140 but does not require preheat ?

There may be options available now that were not on the market when you started doing this back in the day.

Maybe find an engineer that is willing to sit and chat about it.....  You might save quite a bit of time and money with a base metal change and be named employee of the year...

Outside the box my man !
Parent - By Jarhead1 (**) Date 01-10-2020 21:56
Lawrence,

This is a customer driven part in order to change materials they would have to run through an array of AAR testing. Not an option.
As for the employee of the year, I am past those stages in my career.

The savings would be (on my side) production through-put..Manual = 10- per/hr ---- Robot = 60 per/nr. estimated.

Appreciate the input.
Parent - - By Jarhead1 (**) Date 01-10-2020 21:42
Thanks Al,

This is a great concept to trial.
I seen a conveyor on an auction site that i might pursue.

-Thank You
Parent - By 803056 (*****) Date 01-11-2020 20:41
You never mentioned the cycle time for welding, so how much time is available to preheat the parts. The preheat time can be accommodated by place more pieces in que. A simple electric range might suffice. It all depends on the details.

Al
Up Topic Welding Industry / General Welding Discussion / Pre-Heat

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