Beginner Question - Punching Holes

[lostbaka]

*I know nothing\very little about machining and metal work*

For the past couple of weeks, I've been searching for better ways for the guys in our shop to cut\punch holes in steel and aluminum. Their current method is to use hole saws and a Greenlee Slug Buster with kit with wrench. Both methods get old fast. We do have a compnay metal shop but it is across town and better suited for bulk runs and not the small, order specific jobs we would like to start handling in the shop.

Seeing has the only methods I know for putting holes into sheet metal are holes saws, Greenlee, and Strippit, the first place I looked was Greenlee (Didn't go with hole saws because I also need to punch double "D" and rectangular holes). Priced out a Greenlee Quick Draw Flex Driver kit and the custom punch units, but internet searches and too much time with the MSC catalog have got me wondering if I should be looking at other tools.
The Greenlee unit would definately have it uses and will probably be bought, but if there's method that eliminates drilling a hole for the draw stud, that's also good and cuts down on manufacturing time.

Would a small manual turret punch be better? (I didn't know turret punches exsisted in small size and without CNC control until an ebay auction)

What about an Ironworker? Have a machine that can punch plus cut and bend metal would be good and it's relative compactness is also good.

We have an Enerpac portable hydraulic power source (what would be the right way to describe it?) that we use to power a crimper. Could that combined with a hydraulic punch (with a deep enough throat) be a possible solution?

thanks
Frank

[handlewanker]

Hi lostbaka, the heart of the job is the punch and die.
The punch and die are shaped to the form you want to punch out.
For a low volume production,20 to 30 parts, a garage "H" frame type press, about 25 tons, would "do", as long as you have the punch and die mounted in a Die Set.
The Die Set will guarantee that the cutting edges of the punch and die don't interefere when coming together and "nip" the edges, also the part is located relative to the punch for allignment.
Enerpac make a variety of press adaptions and a "C" frame type is what you want, to go with the power pac you already have, but this will still be for low volume production, and is also relative to the tonnage of the powerpac.
This looks like a drill press where the frame is open to the front allowing the job to get to the punch.
The height between the punch and table will determine how big a job you can get under the punch, and the throat will determine the distance from the edge, the larger the distance required the less tonage can be used, or the more massive the frame has to be.
Is an Ironworker a shearing and hole punching machine used by steel fabricators for shearing angle iron and flats and general hole punching?
I don't think this would be suitable for your purpose.
C frame presses are the way to go if any larger volume is anticipated, and a 25 ton model is pretty versatile.
For this way you would need the use of toolmaking facilities and a skilled press operator, because they are dangerous beasts, and collect fingers at the drop of a hat.
Ian.

[metalworkz]

Hello lostbaka,
If the parts you are working with are basically a finished formed assembly or a part with several flanges formed on them it becomes very difficult to process such parts in a turret punch and most other types of small punch presses. The formed features of the part to be punched need to be clear and away from the ram and punching area to avoid unwanted contact when punching etc. Sometimes the die and or die shoe can be raised to allow flanges to clear, and the punch tool holder or adapter can sometimes be extended to punch deep into a flanged part, but these options will also depend on the throat depth of the machine to be used. I have done a lot of part modifications using the Greenlee tools and they do have D and D-D punching tools available and work fairly well for use on formed assemblies and parts too big or to awkward process in a punch press. Greenlee has a hydraulic set for their tools that will enable you to speed up the process which includes a portable small hydraulic tank that connects to the tooling and has a footpedal to operate the tool for punching. If you layout the part and drill all the pilot holes first you can then use a step drill to ream the pilot holes to the needed diameter for the Greenlee tool shank.(smaller tools are 3/8" diameter and the bigger tools are 3/4" diameter I believe) For the 3/4 dia. holes I would use the Greenlee 3/4" punch to go from 3/8 to 3/4. Then just use the hydraulic unit to connect the various punches and pop out each hole location according to print. Care must be used to make sure the hole locations do not drift off location, and if tight tolerances are to be held the dimensions may need to be checked regularly.
Trumpf also makes a great nibbler tool that is electric and uses a 1/2" diameter punch to nibble up to a .125 CRS steel material I believe. This tool if great for making larger diameter holes, cutting irregular profiles etc. This tool will require a fairly large pilot hole around 1.187" diameter if I remember correctly to enable the insertion of the nibbling tool onto the part. This tool can very rapidly nibble large holes that would take much longer to jig saw and it is used with a template to guide the tool so the finished holes can be very accurate, but may need a little cleanup or blending at the edge. It can also be used on finished parts using some preparation of the work area with a tape to protect the finish when needed with good results.
If the parts you are working with are mostly flat then most any open front punch press will serve you well and in a lot of situations I have found a Kick-Press operated by foot power to be very effective and versatile. Naturally if you will be punching thicker material or bigger diameter holes you may need a power press and a 30 ton size is usually enough tonnage for most require-ments. Most die shoes can be modified to add a work table say of 3/16 to 1/4inch thick plate with 1/4-20 tpi holes on say a 2" square bolt hole pattern
that will enable you to bolt down stops to the table for repeat location punching. Using these dead stops along with spacers and hinged or drop stops will add to the work abilities. There are also some X-Y type tables to be found that are a manual type that will bolt to the bolster plate of the punchpress and enable you to set your X and Y stops fairly rapidly.
At the higher end of this type of punch there are some hydraulic N/C type punch presses that are great for higher production in a small shop and I have used the Amada type punch model SP-30. This machine includes a toolholder capable of using 3 tools at a time and has a programable X and Y controller and also has several nice options for cuttouts and larger diameter arcs and circles. This machine will require the use of Amada tools to punch with but there may be some available that are used as well as the tooling.
I hope my rambling has not gone too far and I also hope this information may help you in your endeavours.
Best Regards----Wes

[lostbaka]

Thanks guys!! Wes, the rambling was quite informative and very helpful. The primary material is flat .125" aluminum and 16 GA cold roll steel (well i think it's CRS, it's definitely not stainless). Largest sheet is 24" by 20". This is what made the Greenlee Quick Draw setup standout because there's no need to worry about throat depth.

I didn't know how to deal with the sheet size other than the Greenlee. Most of my searches turned up H frame presses, though I guess one could reorient (sp?) the punch.

My biggest concerns are space the machine takes up, ease of use, and learning curve. I'm not so sure about CNC. We're looking at laser engraver for purchase in the upcoming year and I'm not sure I could swing the purchase of small CNC turret punch with my bosses. (Then again I have no idea how small these machines can get or their price). The patterns to be punched are linear so CNC or another method to speed repetitive tasks would be good.

This is what an Ebay search turned up:
Manual Turret Punch

Would some be kind enough to describe this kind of machine?

thanks again,
frank

[metalworkz]

Hi Frank,
The turret punch in the link you posted looks like capacity wise would work for you, and being as your regular work sheet is 20" x 24" the 12" throat depth would appear to be adequate. I have not operated this particular type of turret punch, but I will speculate that the turret is rotated to position it manually to the station holding the tool to be used at the front of the press directly under the striker. The tool usually has a stripping mechanism included in the punch assembly so the material will srtip off of the punch when the ram is brought to top dead center.
I do not see from the picture of the machine how you will position gauges or stops to locate the holes on the part to be punched, and my guess is there is a small center on the punch tip that can be lowered onto a center punch in the part for hole location. This method is workable but I prefer to have something more substantial to use for work stops(gauge stops bolted to a work table). Keep in mind that if this is the case you will need to center punch each and every hole location prior to punching the part. It can be time consuming and if care is not used to locate the tool in the center punch the hole locations can be out of tolerance. You may very well be able to mount some brackets to the frame of the machine to use for mounting a backstop(for the Y dimensions) and then stops could be mounted along this backstop to locate the X dimensions. If you will need to punch many different hole sizes in your parts the turret may make this easier than a single station punch.
You may want to check around on the prices for the tooling.
Now if your volume of work increases an Amada CNC turret punch may be the way to go, and that is the type I am currently operating. Where are you located Frank? Maybe someone else with experience on these Wiedemann presses will reply with some more definite information about them. I will be glad to help if at all possible.
Regards,
Wes

[chan luci]

Hi Frank,
What is the sheet thickness, application and use? Can u log into www.custompartsonline.com and tell me the qty and other details, attach a drawing? I can see if I can ship them to you.
Regards
Chan Luci