[pyroracing85]

What is a screw machine? I was reading a magazine and I came across a davenport machine article and they said they made screw machiens what do they do?

[ViperTX]

It's a small machine that is designed to do multiple automated operations on small items....let's say that you were looking for a special rivet, that was flush mounted but was designed with a square shoulder to rivet 1/4 inch sheet to a skelton and you needed several hundred or hundreds of thousands.....you would use a screw machine for something like that.

[pyroracing85]

It's a small machine that is designed to do multiple automated operations on small items....let's say that you were looking for a special rivet, that was flush mounted but was designed with a square shoulder to rivet 1/4 inch sheet to a skelton and you needed several hundred or hundreds of thousands.....you would use a screw machine for something like that.

I got ya. so it doesn't make like say 3/4 20 hex head bolt?

[ESjaavik]

I got ya. so it doesn't make like say 3/4 20 hex head bolt?

Yes, it will happily do that for as long as you like. You have to set it up, mount the right tools, feed it the hex stock and sort the finished screws from the swarf.

[pyroracing85]

Yes, it will happily do that for as long as you like. You have to set it up, mount the right tools, feed it the hex stock and sort the finished screws from the swarf.

I got ya. Is that how they do the commerical bolts and nuts you would get at your local bolt and nut store?

[DSL PWR]

Most bolts have rolled threads and extruded heads. (discovery channel)

[pyroracing85]

Most bolts have rolled threads and extruded heads. (discovery channel)

what you mean? What show was that on from discovery channel?

[HuFlungDung]

The "How its made" series covered the manufacture of bolts

[pyroracing85]

The "How its made" series covered the manufacture of bolts

I just tried looking for that section where is it?

[Gunner]

A lot of the nuts, bolts, nails, screws today are run on machines called cold formers. The are designed to press material into the form that is required instead of cutting the material. They are more popular in Europe where the focus on reducing scrap material is much higher. Since you form a slug into what you want, there are no chips or wasted material.

As far as a screw machine. It is a lathe concept machine designed to do high production runs. They come in all different sizes depending on the stock diameter required for your product. We have a dozen or so multi-spindle screwmachines in house. Ours are 6 spindle machines. You load six bars into a spindle carriage. There are also six machining positions inside the machine. A different machining operation is performed at each position. Example - At position 1 the stock is fed to length, position 2 preforms a face pass and center drill, position 3 uses a form tool to put a contour on the OD, postion 4 drills the part to depth, position 5 taps the hole, and position 6 cuts off the part. Each operation is performed every time the spindle carriage indexes to a new position. The index time is based on the longest single operation. In the example our longest machining position is position number 2 where it might take 10 seconds to do the face pass and center drill. That one operation would dictate the cycle time of parts coming off the machine. Every 10 seconds as the spindle carriage rotates another completed part would drop off. If you did the same part on a cnc lathe the cycle time would be a combination of all the operation. Using the above example it might take 60 seconds to drop off 1 part where on the screw machine you would get six. The advantage to a screwmachine is in high production, disadvantage is setup time. You must have volume to offset setup time. The CNC lathe can be setup quickly but will drowned in volume if compared to the production of a screwmachine.

Hope this helps?