Custom CNC-like drill and tapping project

Hello
I want to create an automation for creating holes & and threading on cylindrical metal.
To be specific 3-11mm hole and M4-12 thread on cylinder metal. (Thread - Drill & Tap Chart)

I’m a computer engineer and I already have some experience with arduino and basic electronics, and there are enough info on the net about how to control those motors. I also found about info for the speed needed for drilling / tapping and moving speed for the drilling / threading motor for different holes/threads. But I dont know how much power I will need for motors, and I also dont know how to create more effective product feed. I plan to get 2000 products a day (8 hours) from this automation (About one product in 15 seconds) .

I planned to have powerful step motor as Z axis motion control for two motors putted on the mount, one for drilling and one for tapping. The Y axis will have two mill rods for holding cylindrical metal product and one linear actuator for moving position of the product on the Y axis.

Motor 1 ) For motion control, I decided to use Leadshine M452 for step motor control and I plan to use this motor http://www.exoror.com/datasheet/86BHH114-450p-40Mp.pdf (Holding torque 62kg.cm).
Question 1) Should I use more lower or higher torque motor? Is this right choice for this task. (Holding two motors, and pushing those motors for drilling (in terms of torque), tapping (in terms of precision).

**Motor 2 )**For drilling hole motor & thread motor I don’t know what to use.
I’m thinking about to use drill motor for drilling hole because it has adjustment for speed between 3000rpm and down. And its documents says, it can create 12mm hole on metal. (Bosch PSB 650 RE)
Question 2) Can I use another motor which can be controlled with a polulu 2A step motor driver? What kind of motor I need to use? Or should I use something like Motor 1?

Motor 3) For tapping-threading, I decide to use more low rpm screwdriver motor, something similar to this Error 404 | Bosch Global
Question 3) Can I use another motor which can be controlled with a polulu 2A step motor driver? What kind of motor I need to use?

Motor 4) I think a linear actuator motor can do this task. This will move the product from position A(product feed) to B (drilling) and C (threading) . I mean this kind of motor http://goo.gl/zPzG6p
Question 4) Should I use ball screw and stepper motor for this product positioning or can I trust a linear actuator motor?

Product Feed & Motor 5 I thought about lining the products on vertical line, as the product only has 7mm diameter, I can put 100 products on 70cm length. Actually I had no idea about this product feeding mechanism. I thought about I take one product from bottom by pushing the product on the bottom with linear actuator motor, but I dont know whether this system will work without problem.
Question 5) Should I use a motor which will push the product on the bottom to Y axis (where products move)?

Question 6) Will I need cooling system(pumping motor for oil or water continuously) for drilling & tapping motors?

I could not upload my ugly hand drawing, so I uploaded it here http://i66.tinypic.com/6nt5wo.jpg

Consult a Manufacturing Engineer to work out what torque and power you need for all those cutting and threading operations. There are formulas to work out the power required to remove metal at a specified rate.

Or measure the torque on a conventional machine while doing each operation.

I suspect that you will need kilowatts of power to do all that in 15 seconds. A 2A stepper motor won't cut it.

Tapping threads requires a great deal of torque. Try doing it by hand.

High torque devices bring with them the ability to do serious damage.

I agree with @MorganS that you need to get proper professional advice. Your question goes far beyond the expertise you are likely to encounter here. The tap and die manufacturers will probably be able to help you.

...R

Thank you for replies #morgans #robin2

There are formulas for drilling here (http://www.sandvik.coromant.com/en-gb/knowledge/drilling/formulas_and_definitions/formulas/Pages/default.aspx?Country=us) and here (http://www.mitsubishicarbide.net/contents/mhg/ru/html/product/technical_information/information/formula4.html)

And I thought as the manufacturers are creating those products by hand press drill, it should be hand-power range about 50kg. So that's why I thought for M1 which has holding torque 62kg.cm. Anyway I will ask a pro about it. Thanks again.

Google Tapmatic. It is a device made specifically for high speed production tapping. It incorporates a planetary gearset that on the down stroke you get low speed and lot of torque, then on the up stroke it reverses and quickly removes the tap. These are usually used in a drill press. I you look at some machine tool distributors you can find combined drills and taps that will do your operation all in one pass. Also I would use spiral flute taps instead of straight ones.

Anything you design will be different for each type of metal and alloy. You did not mention continuous flood lubrication. you did not mention how you are going to get rid of the metal chips. You did not mention the need for "peck" drilling to clear chips.

How do you intend to hold the metal while drilling and tapping? Are you going to use a new drill and tap for each job? Or will you be able to monitor the torque increase as a drill or tap becomes dull? Either one will break at some time when too much torque is applied to a dull tool.

Paul

detown: I you look at some machine tool distributors you can find combined drills and taps that will do your operation all in one pass.

My brother gave me sets of these for Christmas a few years ago. They work great on metal thin enough that the drill part breaks through before the tapping section engages. I broke one trying it to drill and tap a piece of quite thick metal. The drill part cannot stay ahead for the tapping part, so jams up and twisted off.

Paul

Trying to drill on a round object is kind of tricky with the bit trying to walk off the part. Might need a drill bushing above the part to keep the bit from walking.

As for tapping I saw a simple setup at a company that did a lot of high volume machining. They had rotary transfer machines where the part travels around to different stations.

At a tapping station they had a geared motor that had a tap attached to the output shaft and this output shaft drove a leadscrew that moved the motor assembly. The leadscrew had the same pitch as the tap so it worked like a charm. At the bottom of travel a switch would change the direction of the motor and the tap would back out.

Search for “spotting drill” to start the hole. And use a 3-jaw chuck mounted on the table of your machine to hold the round material. The chuck can be automated to open and close under computer control.

Paul

From the Original Post

I plan to get 2000 products a day (8 hours) from this automation (About one product in 15 seconds) .

How often will the drill or tap need to be replaced?

I suspect production quality drills and taps are expensive.

A guy showed me a 2mm (I think) drill that had holes down through it for coolant to be pumped under enormous pressure. I don't remember the price but it could have been £50 or £100 each in large quantities. And they did not last long.

...R

Robin2:
From the Original PostHow often will the drill or tap need to be replaced?

I suspect production quality drills and taps are expensive.

A guy showed me a 2mm (I think) drill that had holes down through it for coolant to be pumped under enormous pressure. I don’t remember the price but it could have been £50 or £100 each in large quantities. And they did not last long.

…R

And a special hollow quill and holder to allow the coolant to get to the drill.

The OP really needs to look and a CNC lathe rather than trying to invent a nightmare of devices that will individually fail at inopportune times.

Paul

Paul_KD7HB: And a special hollow quill and holder to allow the coolant to get to the drill.

That seemed so complex that I just blanked it out :)

...R

Interesting project - you don't need much x-y force if only doing vertical operations, but you will definitely need a centre-drill (and possibly an automatic punch) to start each hole if any sort of precision is needed. The tap head probably needs a programmable amount of downwards pressure to start the tapping, and a scale to measure its progress (or you can go the (very?) expensive route of co-ordinating rotation and z-axis drives...)

Does each part need more than one size of tap? If so you have either an issue of tool change or of batching each size and re-alignment on subsequent runs.

I just found this posting again. I studied the OP drawing, again. Now, I see he is wanting to drill and tap the side of each rod. I thought he was wanting to drill and tap the end.

I have to question the source of the rods. Will he have a process for cutting the pieces from a commercially available length of rod? If so, he will need a lathe to finish the ends and trim to a final length.

Drilling the curved surface cannot be done with a regular drill bit or even a split point drill bit. He can use a sharp pointed drill, known as a spotting drill, to start the drilling. Then finish the hole with a standard drill bit. Or machine a flat surface on the rod and then use a split point drill to be sure it does not wander.

Paul

If you want loads of parts, I suggest you find a local machinist with a CNC lathe.

It's not a trivial job.

regards

Allan

Thanks for all who tried to enlighten my way.

First of all, this is not a hobby, it is a need. So I need to solve the problem. I was working with a shop, but they were doing those parts with bench press (after cutting on an automatic cutting machine) one by one. So it is time consuming work for them, and not very profitable. Therefore they do not want to take this job or giving me dates which they dont keep their promise. I got tired of this situation, and I went to some machine manufacturers. This time they gave very expensive prices (between 10,000USD to 33000 USD) for a simple machine (compared to the machines they build). Then I decided to try my chance with arduino, but as I said it is not hobby, just a need. After making some research, I found out some guys who said material cost will be around 1000-1500 USD and they can take 1500 USD for the project after one week negotiation (including mechanical design & PLC automation). We decided to meet up, and discuss final details and start on the project, but it seems they were outsourcing this project to someone else, and they tried to change their words as if they were offering me hobby project not industrial automation. So the guy who will make the project tried to increase prices, triple.

Anyway I searched a lot about tapping, and 0,75Kw (or max 1kW) servo motor can handle M8 tapping. I dont need high torque for Z-axis movement motor (Probably 2 or max 4 Nm stepper is ok) . I also found out there are already ready-made tapping solutions for machine manufacturers.

By the way, I also searched what alternatives can be. Apart from this automation, I think it can be also solved with a CNC which has enough power for M8 tapping. I mean creating a 50cmx50cm mold to hold products on CNC table (50x50cm probably will take 2500pcs in one load). So if I will have such mold, CNC can do drilling operation, then changing the head for tapping etc. For this reason, I searched manual mill to CNC conversation. I found out Proxxon MF-70 - Arduino conversion kit. It is about 800USD solution (both kit & mill), but its motor does not have enough power. Firstly I searched about whether I can put a powerful servo on this CNC after conversation, but I did not find info on that. Therefore I look for more powerful CNC mills conversion projects. I found SIEG X2 , it is just perfect for the job. But I could not find local kit (I have local kit for proxxon) for SIEG X2, and one American supplier seems to me not so fast for delivering the kits. Then also found out, there is one guy who sells the plan but I really get tired about this project.

Then I looked up some machine engineer who can design/draw the machine. I searched on freelance sites and I found out one guy exactly the service I was looking for : https://www.peopleperhour.com/hourlie/design-any-machine-according-to-your-needs/122541?ref=search

But he did not interested in, as he prefer to make all machine himself and earn more money. So I did not understand why he put such listing on that website if he is not willing to do exactly the thing he was promising for the fee.

After this incident, I gave up on machine designers as I understand they want to get very good money with little effort. So I called the company who has lowest offer about 7500USD for the machine. The design was with rotating table, and it was planned to finish 10 products/minute. And it also had vibrational loading unit, (after loading 10,000 small units, it will order those products with circular vibrational feeding unit) . Anyway I asked him whether he can create more economical, slower (and probably less efficient) machine which will solve my needs and waiting for answer.

One last thing about my research is that, there some tapping solutions who need an operator : swing-arm tapping machines. https://www.youtube.com/watch?v=DbVYJIE2yg4 It has table and handling unit, so instead of CNC, a human can do this task with a mold which products are hold tight in small area. Those are about 1000 to 2000 USD.

Actually I still think MF-70 & conversion kit is good starting point to learn about CNC as I dont have any CNC machine. And it is not expensive for such an experience. So I can decide whether to go with SIEG X2 conversation route or ordering custom machine from a machine manufacturer.

Having a machine shop I would ask some basic questions.

What material are you working with?

How many different sizes?

Thread call out?

Edges of hole need to be deburred?

Material is easy to cut metal bar, e.g. 11SMnPb30 (9SMnPb28) 11SMn30 (9SMn28) 11SMnPb37 (9SMnPb36)
Firstly two different size, then I may need different thread size on the same products
Thread call out, I think manually done products were deep threads than normal, because the product is used where they get direct holding force against gravity. For example, it can be M8 , 6.75 drill , 1.25 ( I’m not sure about those)
Yes there should be 3rd motor for cleaning out the entrance of hole. Actually it should be done on both sides for larger sized product because in small sizes, when screw goes through the hole, problem is solved after a couple of turns. But for M8 part, it should be cleaned both ways.