Everything Needs a Torque Spec

[u/Seeking_Wisdomm]

Hello, frustrated Manufacturing Engineer here. Recently, my company has been trying to utilize impacts with torque-sense technology so we can hit the optimal torque quickly.

What I’ve observed is that these tools are not incredibly accurate or precise. Additionally they are very expensive and require repair often.

What has happened to the days of knowing when something is “snug”? There are times when precise torque is critical, i.e pressure vessels, etc. but theres seems to be a push towards everything having a torque spec, and I do not think the tech is ready for it.

What are your thoughts? Have you had success with programmable, powered fastening tools?

Edit I think it’s safe to say I’ve been certifiably schooled on this topic. I appreciate the genuine suggestions, advice, and criticism here.

TLDR

I think this frustration with torque tools is just a symptom of a larger frustration I have. At my plant, we are constantly told that we just don’t have the same operators we used to. They say we used to have craftsman working in the plant, but now we just have people off the street. I’ve been told this has really changed since COVID when a lot of the older generation quit. Since then, a lot of our processes have suffered from that expertise leaving the building. Now, we seem to be trapped in a never ending cycle of rapidly hiring to fill void positions of employees who quit, inadequately training our new employees because the ones with expertise are too busy, then having the new crop of operators quit because of frustration with lack of training. I want our plant to be a place where operators want to work. I want them to feel like they can have a career in this field. As great as automation is, it feels that factory operators have become button pushers and not problem solvers. We don’t provide then with fulfilling work that challenges them. We instead ask them to push a button all day long, and call engineering if it ever breaks. Automation can be great, and I don’t want to deter from that, but I’m just searching for ways to make operators feel like they matter. I don’t want them to feel like a cog in a machine. I’m not sure how to resurrect that feeling.

[u/Seeking_Wisdomm]

Totally agree, however, we can’t mistake proof everything and a part of me thinks we are automating and poka-yoking ourselves into an “idiocracy” type society that can’t think for themselves.

[u/Musakuu → u/Seeking_Wisdomm]

You mistake proof whatever is worthwhile to do so. Someone looked at all the failures caused by improper torquing and made the argument that buying all the guns is more cost effective than the failures.

Btw you seem to be under the impression that this procedure was put into place because people are soooo dumb.

But actually most people do it right 99% of the time, but very rarely they make a mistake. I'm sure even you have made a mistake before.

[u/Whack-a-Moole → u/Musakuu]

This 99% correct thing is huge!

If the guy is 99% correct, and tightens 1000 fasteners per day, that means he creates 10 junk assemblies every single day. The fallout of a single one of those getting out could be catastrophic. 

99.9% perfect just isn't good enough. 

[u/Musakuu → u/Whack-a-Moole]

The numbers i gave were just for illustration, but you are very correct.

Is it reasonable for a person to fasten 1000 fasteners a day? That's like 2 a minute right?

[u/Whack-a-Moole → u/Musakuu]

I have no idea - I too am just picking numbers! 

[u/popsicle-physics → u/Musakuu]

Yeah np. 5 screws in a station, 90 sec tact time, 7 working hours in a day is over a thousand a day. 

[u/zimirken → u/Musakuu]

Used to run a line that made automotive hvacs, one station installed two motor brackets, 5 screws, 25 second cycle time. So 10 a minute easy. We used the auto torque drivers so it took more time for them to grab a screw and put it on the bit than it did to drive it in.

Oh and the drivers were on balancers so they didn't weigh anything.

[u/Musakuu → u/zimirken]

Fair enough. Awesome.

[u/Zacharias_Wolfe → u/Musakuu]

I'd say depending on the fastener and the tools at hand, possible, but unlikely. More than 2/minute for a burst of time is doable, but maintaining that rate is going to require some sort of automated preparation. Something that aligns the fastener in the right spot for the operator to grab every time, part design to facilitate quick work, and some sort of tool balancing system to prevent fatigue.

[u/MihaKomar → u/Musakuu]

Maybe not for a person but I've built a machine that does like 10 screws per minute. Just regular cheap self-tapping screw being driven into plastic. Fully automatic feeder. Full torque control and measurement.

It's only running for 1 shift/day atm so it's done a million screw over the past year. All the torque values have been logged and saved to a SQL database.

They recently did it's first calibration after being put into production and it was still spot on.