PDA

View Full Version : How are small nuts,bolts and screws made?



Stephen Tashiro
01-19-2011, 2:30 PM
It would be interesting to see a video about the manufacture of small nuts,bolts and screws, the tiny sizes that are found in equipment like digital cameras. It's tempting to think that you could build a "factory" for such things like that in your garage, or even on your kitchen table.

Orion Henderson
01-19-2011, 3:07 PM
For the most part they are turned. Traditionally on equipment like Brown & Sharpe screw machines (lathes). Here is a link: http://www.youtube.com/watch?v=T9uQ7v-I8Ng&feature=related

Brown & Sharpes' are still widely used and are exceptional machines. You absolutely can set one up in your garage. That said, they are loud, smelly, and require a whole lot of TLC. Screw machine set up is a pretty specialized skill and it doesn't translate to or from standard machinist skill sets.

Current CNC screw machine lathes can do a whole lot more operations and can eliminate a lot of secondary ops in one passs. They cost huge amounts of money: http://www.youtube.com/watch?v=bYf15b8tbv0

I have seen both in operation many times and it is pretty neat. We used to own a couple Brown & Sharpes' but eventually got rid of them. We had a WWII tank repairman to operate them, when he retired it made sense to find someone else to do the work (local shop). He had some stories!

Dan Hintz
01-19-2011, 3:14 PM
Orion,

While the general technique may be similar, these days screws are manufactured in high-speed CNC machines that press the threads in from a standard blank via rotating "stamps" on either side (similar to the knurling process). Many screws per second are cranked out by these machines.

Orion Henderson
01-19-2011, 3:38 PM
I saw several CNC's in operation back in December. They started with bar stock-round, square, etc. Is this the same thing you mean? They were running brass, stainless, and even plastic parts. thye set them up and left for the night. When they came back in the morning they inspected some parts and set up the next job. To be sure-they weren't cutting wood screws, but various components for furniture hardware, stoves, and even automotive applications.

The cutting tools were quite different than what we use, and the process was (much) faster, but the concept was more or less the same. For a garage set up I think an old Brown & Sharpe is about the only affordable option, no?

Dan Hintz
01-19-2011, 3:45 PM
Yep, starts with bar stock. Saws cut to length, then the head is formed by a press. Finally, they're transferred to what amounts to a knurling machine to press the threads into shape. No material is added/removed once the bar stock has been cut to length.

This obviously applies only to metals that are easily formed via presses... others, such as titanium, are more than likely still cut in a more traditional manner, though I cannot say for sure (never saw titanium bolts being worked on).

ray hampton
01-19-2011, 7:08 PM
I was a hand-screw machine set-up and operator during 1973, the automatic are very noisy but all of them give off a lot of heat----we kept the exit door open until the temperature drop to the teens F

Eric DeSilva
01-19-2011, 7:13 PM
If I go to buy brass screws from McFeeleys, it gives me the choice of cut threads or rolled threads. So apparently there is variation.

John M Wilson
01-19-2011, 7:53 PM
While some specialty screws are manufactured on screw machines or metal-cutting CNC's, the vast majority of mass-market screws (and nails) are made on a machine called a "cold-header". This machine has more in common with a stamping press than a machining operation. The machine starts with wire of a particular diameter, then forms the head in a multi-stage press-forming operation over a series of horizontal dies. Once the head is formed, the last few steps size the shank, and then roll-form the thread. These machines perform at a ridiculously fast speed, and the screws fly off in a near constant stream. Although the machines are incredibly expensive, and not very versatile, when one is set up & run for high volumes, no other process comes close in minimizing cost per screw.

greg lindsey
01-20-2011, 12:48 AM
Not trying to hijack this thread, but, I found a place called Alpha Threaded Products, here in Houston. They carry or manufacture any bolt, nut, washer, rivet or just about any fastening product you could dream of or they will make it. Just FYI in case you ever had a need for the such.

Bryan Morgan
01-20-2011, 2:27 AM
It would be interesting to see a video about the manufacture of small nuts,bolts and screws, the tiny sizes that are found in equipment like digital cameras. It's tempting to think that you could build a "factory" for such things like that in your garage, or even on your kitchen table.


The show "How its made" on the science channel has shown this.

gopal sharma
01-16-2013, 2:33 AM
Really informative post. Thanks for sharing this information about nuts and bolts.