Heavy Duty Thread Inserts for Platens.

Davis In SC · Aug 14, 2017

Stripped threads on cast iron molding machine platens. Looking to drill and tap for inserts, but standard inserts are too short, they need longer thread depth.
These threads will have clamp bolts tightened in them several times daily. Nothing in the McM Carr book looks good. Any ideas for a source? Sizes needed would be 16mm, 20mm and 5/8-11.

Erich · Aug 14, 2017

How about heavy duty keen serts?

Key Inserts – Heavy Duty, Steel (Inch) | Carr Lane

SteveBausch · Aug 14, 2017

"Longer" is not an absolute value.

How long?

Is the intended use of the machine deviating from the maker's expected usage? If so, you are on your own.

May have to make your own inserts, keep them in place with "dutch key" set screws until replacement is required.

The bolts should be sacrificial, not the internal threads, or studs should be used, but there's a good reason why not, correct?

The insert can screw in, or the dutch key set screws can resist torque and pullout. It works for taper-lock hubs...

muckalee · Aug 14, 2017

Custom made to your specifications. Cast iron (?) is probably cracked out farther than you think. Make the OD 2-3 times larger to get away from the damaged parent metal and any length you want. Coarse threads on the outside and your needs on the inside threads. Choose the locking methods to suit. Loctite or locking screws, etc.

Davis In SC · Aug 14, 2017

SteveBausch said:
"Longer" is not an absolute value.

How long?

Is the intended use of the machine deviating from the maker's expected usage? If so, you are on your own.

May have to make your own inserts, keep them in place with "dutch key" set screws until replacement is required.

The bolts should be sacrificial, not the internal threads, or studs should be used, but there's a good reason why not, correct?

The insert can screw in, or the dutch key set screws can resist torque and pullout. It works for taper-lock hubs...

Application is on a Nissei Molding Machine, Only a year old, but many of the holes have stripped.. Odd thing is, there are 6 more Nissei machines in the same plant, some over 20 years old. Most of them have suffered few if any stripped holes. Rumor has it that the affected machine was built in their China plant, instead of Japan.

I want inserts that are at least 2X as long as major thread OD.

ManualEd · Aug 14, 2017

In applications where threads are repeatedly stripped (A 1" air impact shouldn't be used to start a 3/8 bolt, go figger) I make up my own insert, then Loctite them in.
If Loctite isn't an option due to heat, you can use a lower strength Loctite, drill and tap it where the insert meets the part and put in a setscrew.

Makes it simple to change them out the next time, and you can customize it however you want.
I rarely find a Keensert or helicoil that will fit the job properly.

Milland · Aug 14, 2017

Davis In SC said:
Application is on a Nissei Molding Machine, Only a year old, but many of the holes have stripped.. Odd thing is, there are 6 more Nissei machines in the same plant, some over 20 years old. Most of them have suffered few if any stripped holes. Rumor has it that the affected machine was built in their China plant, instead of Japan.

I want inserts that are at least 2X as long as major thread OD.

Davis, if making your own inserts is in the cards, I have some M33 (33mm OD x 3.5p) hex bolts with 75mm useful thread length at the 12.9 ratings. Should be able to get two insert blanks per bolt, and there's no worries about stripping them. Just have to deal with drilling/tapping them in the hard state, a little more that regular US grade 8 cap screws.

If they're of use, I can flat-rate you some at a reasonable cost. Let me know...

Milland · Aug 14, 2017

Davis In SC said:
Rumor has it that the affected machine was built in their China plant, instead of Japan.

Now there's a shock [where's the sarcasm emoji?].

guest · Aug 14, 2017

Davis In SC said:
...Looking to drill and tap for inserts, but standard inserts are too short, they need longer thread depth.
These threads will have clamp bolts tightened in them several times daily. Nothing in the McM Carr book looks good. Any ideas for a source? Sizes needed would be 16mm, 20mm and 5/8-11.

Helicoils come in up to 3xD in all the sizes you list.

Here's a 5/8-11 that's 1-7/8 long:

1185-1CN-1875 5/8-11 H-COIL FREE RUN 61226 - MSC

If you give Mcmaster the p/n's I bet they will order them for you.

Here's the catalog:

http://www.helicoil.in/pdf/helicoil catalogue.pdf

Milland · Aug 14, 2017

When dealing with brittle materials like cast iron I prefer solid inserts for repairs. Helicoils are my preference when the base material is more ductile, like aluminums and steels.

Given that this seems to be crap CI, a larger base diameter for the insert seems best.

boslab · Aug 15, 2017

Seems like if the platten is off you can bore out and custom a top hat insert, the rim on the back of the way it clamps to spread the load on the crumbly cheese iron?
Mark

Modelman · Aug 15, 2017

I would suspect the platen is 4"- 5" thick, possibly with details on the back that preclude drilling through holes. I think this sort of repair is normally done in place by clamping a magnetic drill to the platen.

Dennis

adama · Aug 15, 2017

Kenserts are the best option, 2d gains you next to bugger all over 1.5D when it comes to real world thread strengths.

WHHJR · Aug 15, 2017

What ever you choose to do, sink the thread one or two threads below the surface. While you are at it what about studs instead?

3ó

Davis In SC · Aug 15, 2017

WHHJR said:
What ever you choose to do, sink the thread one or two threads below the surface. While you are at it what about studs instead?

3ó

Different holes are used on a daily basis, the most frequently used ones are trashed. I told the customer they need to complain to the Nissei rep. As mentioned before, similar machines 20 years old have very few of these problems.

Milland · Aug 15, 2017

Davis In SC said:
Different holes are used on a daily basis, the most frequently used ones are trashed. I told the customer they need to complain to the Nissei rep. As mentioned before, similar machines 20 years old have very few of these problems.

If you do wind up repairing this machine let us know what method you use.

Danny VanVoorn · Aug 15, 2017

I don't understand the 2X length on major diameter; believe full strength is achieved at a 1:1 ratio?
I have a lot of experience with the Kingsert/Keysert type inserts, had them in all the 3 spindle gantry Cinncinnatti milling machine tables at the shop I worked in. They flat work but one plus is their easily changed when they do get damaged, drill the insert below the lock keys and pull them out with an easy out.
Dan

Davis In SC · Aug 15, 2017

Milland said:
If you do wind up repairing this machine let us know what method you use.

May be a while, but once a few more holes strip, they will be forced to get repairs. If we cannot find suitable inserts my suggestion will be to make up/have made inserts from 4140 or similar with a thread length of 3X or so. Various size molds and mold clamps can mean some bolts go deep. I will even clear a deeper hole a bit over major OD for clearance to go deeper.

adama · Aug 16, 2017

^ If there bottoming them out then that could well be the real cause of the problem! Thats normally how milling machine Tee slots get fubbered!

Heavy Duty Thread Inserts for Platens.

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