How to hire a CNC Machnist

Ok,
Here is something that may be useful for some of you here if everyone responds.

Our company under the current hiring policy is only having about a 30% success rate with CNC Machinists. I would like to put together a exam of some kind with questions that pertain to CNC machining to see if they know as much as they say. I will probably put some pictures of Micrometers and verniers set to a dimension and see if they can tell me what the measurements are.

You get so many bullcrappers it is hard to sort them out evidently. I wish they would just let me interview any prospects.

Anyone have some question suggestions?

Are you looking for someone who can do there own set-ups and programming? This can be a challenging individual to find. If this is what you are looking for your idea of an exam has gone through my head many times too. First off you need to find someone that is strong in math and can read prints in their sleep. Secondly it is very helpful if they are familiar with the types of controls in your shop. After that it gets technical.
Things they should know are:
1) Good understanding of cutter compensation
2) How to use sub programs
3) Knowlege of various drilling cylcles
4)Macro skills are advanced but are a major bonus
5)Have good set up habits

These are the basics and should be used as a starting point. If you cannot find a qualified individual than your next best bet is to find someone that is trainable and invest in them.

Take Care and Good luck

ARB

I was around NC when it was nice and new. The shop management sent a Machinist to "NC school". This was usually the course offered by the manufacturer of the machine.

That machinist had charge of the NC machine and trained other machinists in the shop, usually with some help form the machine manufacturer also.

The point here is, in those days Machinists ran NC Machine Tools.

I have intentionally stayed out of the CNC thing, I have too much fun running conventional machines and I manage to stay in business.

I am glad that you posted because I read about the CNC stuff in the trade magazines and know that there is a lot of very good high level software that makes running the things much easier than they were to program and run in the days of "G" code.

Now I see that there is Trouble in Paradise.

Computer Numerically Controlled Machine Tools are still Machine Tools.

It looks like it still requires Machinsits to program and run them.

Somebody somewhere is going to have to train Machinists aren't they?

ARB,
Maybe I should have them


1) write a line of code that would represent a canned cycle for peck drilling

2) explain cutter comp and give an example program of how you would use it to machine around a 2"x4" block.

3) explain the use of sub-programs

4) identify these codes:
G17
G54
G41
G03
G98
M03
M08
M30


5)maybe have a sample of one of our prints and see if they identify what a section view is.

6) identify on the same print what the surface finish requirements are.

Any other suggestions??

you forgot one thing:
hire on the spot anyone you run across that can do all of the above
how about you throw them a print, point to the machine tool, and see how much they stumble? If you run generic fanuc stuff they should be able to pretty much adlib it if they can't get it running.

First of all, rather than pictures of micometers and verniers I would hand them a completed part with the drawing and all the nessessary measuring equipment(ie:mic's,verniers,depth gage).I would have them inspect the part for errors, while recording all of their findings.

It is easy to tell a good machinist just by the way they handle their tools!

If they don't request a certified gage block to calibrate the the measuring tools,show them the door!

Traceman,
As the weed sees it:
You should have a team to interview people for your department including some of the people that do the job being offered. A prepared list of questions that can be asked verbally and answered verbally by the team is a good idea. A written test is very intimidating to some people that may be good, but not so good at taking tests. Be prepared to train on your equipment, and let a guy know what you expect. I have been involved in coordinate measuring machines since the early days of resolver type machines. I know that some very capable inspectors just can not grasp it at first. Factory training programs are no substitute for hands on and lessons from some one that is competent with the equipment. I would never ask a job applicant anything software specific, only questions that are universal in nature to this type equipment.
I have a small shop with some small CNC machines. The have conversational controls and are very friendly to use. I got a guy from another shop that only had experience on one control. At first he was freaked out by my machines but after a few days he had it mastered. I had to give the chance. Now I am very happy and confident he can go out there and machine anything I need with no help. But I made sure he had basic understanding of drawings and good shop skills, such as tool selection and job set up. And I am open minded and know very well I can learn something from almost anybody. He was not proficient with GDandT, but I can understand that and we are working on that. I suspect in a short time after reading some material and me showing him and explaining that soon he will know it as good as anybody. Point is training. With the limited or non existence of apprentice programs a totally qualified person is hard to come by, and is usually going to be working already at a bigger shop, even though I compensate well to all that are part of our team, many qualified men still prefer the big joints. I have been and still am the employee and I can see both sides clearly. You might even consider giving a guy with no experience a chance, if you have the patience, time to train and supervision that can go beyond just being the boss, that person can be molded into a proficient member of your organization.

I often wondered if I could get a job as a machinist. After running this shop for ten years mostly alone and making the money to buy machines and learning them by trial and error I still could not answer any questions g code specific. I think that will change here shortly with our new machine and I will have yet another software issue to face. I always wanted to be a machinist, I just got stuck in inspection and I liked those tools as well. It paid off because although at first my machining skills were nonexistent. I had the advantage of knowing what it is supposed to look like and what is acceptable. So on behalf of any other inspection personnel that would like to give machining a try I encourage you to consider other backgrounds in industry to fill your position.

I have taken a few written tests regarding inspection of machined parts. Some were easy and some down right brutal.
One I remember as being difficult was from an east coast helicopter outfit. All kinds of questions about special processing and Question were you had to write a detailed procedure on inspection of a difficult piece that had almost no tolerance. Many question on the inspection of system 22 threads, (a very detailed analysis of every element) as well as quality system auditing. I was sweating profusely when I came to the question “How do you inspect the depth of the case on a carburized part?” Gave it my best shot. Test specimen sectioned and examined with a Knoop type hardness tester. Silly wild ass guess but good enough. I really enjoyed working for those folks out here on the west coast, and got to go into many differant shops that were making their parts. I loved that job and had a vary good relationship with the suppliers. I wish it had never ended but it did, and I became a better inspector and had more apreciation for the guys doing the work after making big piles of scrap myself.
Good Luck

Having been on both the hiring and hiree end of CNC machining I can say that I see 2 initial paths to take when hiring a CNC machinist.1) Hire someone you know who has the abilities necessary 2) Interview the individuals considered for hire taking into account your unique situation.
First, ask yourself what kind of employee you need. Obviously, timeliness, appearance, organization skills, and other seemingly "expected" employee traits cannot completely be known until you hire the person; you can usually rely on references, and of course "gut feeling" as to whether an employee will be able to meet these basic criteria. But what you really need to know is can the person fulfill your expectations for their position.
Do you need an operator to set-up EIA machines from existing programs or programs that someone else has written? If so, they will need to be familiar with setting up the machine to run.
Of course, as was mentioned in another post, there are talented employees out there that have never set-up your exact machine before but can draw upon their knowledge of the machines they have set-up to learn quickly. My first "G-code" machine to fool with was a Haas VF-3. After changing jobs I was easily able to assimilate (in the matter of hours)the set-up of a Mazatrol EIA(Yasnac MX-3) machine because of certain constants from machine tool to machine tool. Where are tool length and diameter offsets stored? How does one get the machine to record those offsets. What are the procedures for power-up? etc...
Do you need someone to do the whole cookie? Hand them a print and a job order and not see them again 'til they've completed the job and are looking for another job order? This is where there are two close yet separate paths to look at. Are your machines conversational? Hurcos, Mazaks, et.al. are great machines because a proficient operator will be able to do the entire setup at the machine, including programming. Are you running "G-code" machines? The machinist will have to be familiar with CAM programming, computers in general, and some sort of CAD program in addition to setting up of the machine.
Proficiency in math is more of a bonus than anything. I use trig almost everyday and can't see how anyone could get by without it, but not too many people would be able to say, figure out how to find the locations of milling a hex or the tangency points between a straight line and a partial radius. Ask the machinist what tools he uses most. Aside from the obvious answer--my head-- I think a good calculator should be in the list as well. When I was doing a little moonlighting, I tried to figure out what tools I needed to bring from my dayjob. At first I brought most everything; prepared for just about anything. I soon settled into bringing the tools I used most; 12in. Calipers, TI-35 calculator, Metric & Standard Allen wrences, notepad, and pencils/pens.
Resumes are a prospective employees' means of showing off their supposed abilities. They are necessary, but I am loathe to compare people from their resumes only. I consider myself a good machinist and employee and my resume doesn't look nearly as great as some that I've received. Maybe I just have a problem putting together resumes and others have a better knack for it. Nothing beats meeting with the employee face to face. As a general rule, most companies do not put their names in classified ads, some include only a fax number, some go a little extra and include their address. History has shown that I've hired from the resourceful individuals that figured out where we were and came in to talk about the position and hand in their resumes themselves. I can use the internet to tell me the name and address of the fax number that I see in a classified ad, but the fact that that company did not include any other information is indicative of their probable aversion to having people show up to talk to them, so I don't do that; I figure it's their loss. So leave a "clue" in the ad as to where you are, and a few resourceful people (usually the people you want to hire) will show up. I've been busy before when these people dropped in, so we didn't get a chance to talk right then, but I definitely scheduled an appointment to interview them. Another idea we've been kicking around is posting job openings on the internet only. That way,we think, we will see fewer applications, but will probably see a "higher quality" of employee applying for the position. Obviously someone who knows how to use a computer, and is a little more "upper echelon". We haven't tried it yet, but if you do, and it works, pass the info along. Hope this helps.

i would give them a print, show them the machine, and say have at it.
just my 2 cents.

Maybe I should explain a little more about our company and our machines.

We are a Fortune 500 company that does Oil Field equipment for Shell, BP, Mobile Exxon, and Kerr Mcgee.

All of our HBM's are made by either G&L or Lucas. THey all have been retrofitted to the same control which is a G&L 8000 series.

We have a very strict (towards managers)HR department so once you get someone hired in it takes an act of Congress to get rid of them.

Willie, besides #3 I feel all the questions I posed are something every good Machinist should know. G codes may vary but most of those are the same on all the machines I have ran. They should have a good understanding of that stuff to even be applying for a 1st class CNC Machinist position.

I like Artics idea as well. Give them a part with known defects and see if they can find them.

We get people in here that have 20 years experience but it has all been button pushing with little set-up or programming experience. We are not hiring button pushers. We have a group of Programmers and they supply set-up sheets. The operator set-up the Job and proofs out the program. He is responsible for his own inspections. Our parts can be a bit tricky to inspect on certain features. Our parts normally take from 100-600 hours to machine just on the mills so mistakes can become quite costly if not caught when they happen and fixed while on the machine.

Our pay is probably tops for Houston and we expect top Machinists. I feel Resumes are a joke since you really can't question the other companies too much about how the persons performance was there. All they will say is if they worked there or not.

Keep the responses coming. I am finding this all very interesting.

Traceman,
good to hear from you. I like your idea of getting them to identify basic g-codes. As you say their are a lot of them that are machine specific, but they should be able to correctly identify the standard codes. Such as g81, g83, g76, g84/g88, g89, g99, g01, g02, g03, g17, g18, g19, mo3, mo4, mo5, m98,& m30 They should be able to describe in detail what the tool length, and dia. offsets do to a program/part.I think they should be able to describe the dynamics of feed, speed, ipt, ipr, and all of the equations to get that info. I also agree with the inspecting of a good or defective part. That is a sure way of telling whether the machinist knows his/her sh#$%. I generally give them a print, show them the tools, machines, and say go to it. (MANUALS ONLY) Unfotunatly you cannot do that with a 200k cnc hbm. Hope you get this sorted out. BTY if you compose a list, I would love to see it. Take care, Doug.

traceman,
The only problem with id'ing the g codes is you may have to do some homework yourself. G codes move around a bit control to control. for example G98 in fanuc is not G98 in a Cincinnati Vickers control. G98 in fanuc means " return to the start point at the end of the fixed cycle". G98 in Cincinnati means " in machine coordinates". M codes definitely vary from machine to machine when you get past M09. You are in a unique situation running large equipment, expensive parts, and 2 levels of quality, scrap and perfection. Subprograms are a personal thing, depending upon control memory available and what you are doing. Personally I never use subs unless there is a memory issue. It sounds like your best route is " word of mouth advertising". when you need help, ask all the knowledgable people in your shop that you trust if they know anyone looking. let it be known pay, hours, etc. Your local trade schools may also be able to help you devise your test.

I was in your shoes not to long ago, our shop has grown to over 16 people from when it was 4 of us. It to is well paying and takes an act of god to get fired from once your in. We do all prototype work here and that requires people to be a jack of all when it comes to machining, plus all of the cnc mill guys have to know how to utilize our cad system. What i did was make up somewhat of simple test that an actual cnc machinist should know. Questions would range from proper method of sqauring a block, how to use an edge finder, if given a sine bar and it requires 30 degress how big of block do you provide, you have a 1/4-20 tap running 200 rpm how fast do you program the feed and what g code do you use. There would be some common geometric tolerence symbols, where you fill in what there name was and what that meant. If you have a 45 degree angle and side a is .500 long how long

Whoops my post screwed up....
Anyway is side A is .500 how long is side B? Duh......500 also. Give them a calculator and get side C, see if they know the simple pathagory and therom stuff. We will get a team together of alteast 3 people for the sit down interview and all will ask questions trying to feel if they can work with this person. Take your time while interviewing becuase your going to be stuck with them. Good Luck.........Chad

TumbleweedTim,
Micro hardness test (Knoop Test) is the only way I know of to check the case hardness and thickness. Hiring a good cnc machinist. Good luck, there are a few good ones out there. I always look for a machinist with some conventional machining background. The cnc part can be taught in a fairly short amount of time. Knowing how to approach a job takes years. In my travels I have come across a few of those English blokes who have been thru an aprentice program in England who were pretty good machinist's. They will try to put a macro in every program you have and are a bit rough around the edges (cocky) at first but after working around the for a bit there allright. I hired a neighborhood kid age fifteen at my job shop with no experience to work in the summer while he was out of school. This was in 1990 he is now one of the best machinist's and hardest workers I know. Inspector wanting to be a machinist, I don't blame you. Inspecters are usually the bearer of bad news, and of course it is the inspecters fault that the part's don't ship.
I have been a machinist for 25+ years and for the last two years I have been in charge of Q.C. I would much rather make the part than check it.

Traceman,
We have conversed before.

You even once said:
"You should come down and interview Bryan. We need some more machinists that have experience with the big machines. Especailly G&L. You might like Houston."

Should I actually consider that in my upcoming vacation next week?

The description you gave of your operators is a description of my position. Only differnce is I have to program as required also. I can share some of my programs and subroutines as a "resume" of my work.

Bryan,
By all means, send me a Resume and I will forward get it to the Shop Manager since that is what he wants to see.

E-mail me at [email protected] and I can give you the info. We are going to hire some over the next few weeks for the 2nd shift.

Two things:

1) About 16 years ago I helped with a night class at a community college that taught machine shop basics and touched on beginers CNC. There was a test that was given out the first night of the class which tested for basic knowledge and gave us an idea of how to structure the class. At the end of the 8 weeks, a similar test was given to measure the success of each student. Being the Pack-Rat that I am, I probably still have a copy of the tests somewhere. I'll look around and see. They may be useful.

2) Involve the other machinists in the interveiw/hiring process. Let them help structure a "test". Who knows better than the guys who deal with it on a daily basis what is most needed. We did that at the last place I worked and it worked well. There wasn't a written test but two or three of the machinist's and one programmer interviewed the prospective employee in an informal chit-chat manner. Try to make the new guy comfortable and at ease before hitting him with the hardest questions. I've found that there are some good machinists that don't do well on tests. I hired a guy that would have failed most of the test questions mentioned but he became one of the best we had. You want someone with hands-on knowledge, not a book smart test taker. You can get a feel for the guy by being casual and just talking shop. We even let the interviewee spend a few hours in the shop, on the machines, with the same machinists who helped with the interview. This is valuable. Your top notch machinists will be able to weed out the bulls**ters with ease. And when you do hire someone, the rest of your guys will help get him up to speed quicker because they helped pick him out. It is in their best interest, too, that he succeeds.

E-Stop,
Excellent point about getting buy in from the other guys in the shop. This really can make or break the new guy. This discussion gets better and better.

ARB

There is a test that is used for exactly that. Contact Steve Rose of The Rose Training Systems.
www.cnc-training.com
This is a very good test of not only their CNC knowledge but their machining knowledge as a whole.