Buying 1st VMC

[schurches]

I'm looking for some advice on purchasing a vertical machining center. I am new to this field so any help you give will be greatly appreciated.

I will be drilling and tapping for the most part, with milling in the works some time down the road. We work with steel (HR) plate up to 2" thick and some structural steel (beams, channels) of various sizes.

What types of machines would you recommend for these applications?

Thanks

[Geof]

What size are your workpieces?

Down the road you will want to mill what material and what size?

[schurches]

Smallest 1"x4"

Largest 24"x60"

Same for drilling and milling.

Thanks for the response.

[Geof]

The reason I asked about size is that Haas has gantry machines that are available with a 5000rpm spindle and do fine for drilling and tapping. If you are dealing with big pieces up to 6 feet by 12 feet and you are only drilling and tapping these machines may be the most cost effective approach. They are not suitable for milling steel unless you are happy taking very dainty cuts, they just do not have the rigidity. For true milling on steel you need a proper VMC and one that has a 60" capacity is quite big; I cannot really give any advice here.

[RICHARD ZASTROW]

Worst case 24" X 60" X 2" 800+lbs plus workholding probably 1,000 lbs. plus drilling thrust = ? makes for a pretty heavy table load. If you are going to do heavy milling cuts, the ballscrew/nut/servomotor are also going to be substantial as well. You are probably talking 50 taper or equivelant for spindle tooling. There are quite a few machines in that area. What are you looking at?

[schurches]

I've been looking at Mighty, Makino, Haas, Mori Seiki, but that's the problem. I don't really have a firm grasp on what's good and what's not. I have read plenty of bad things about Haas.

[Caprirs]

Haas makes good machines for their application. They are not designed to be top-of-the-line machines because most machining operations do not require top-of-the-line performance. They are entry level machines that make shops a lot of money and are generally well supported.

The Makino and Mori are top-of-the-line machines as reflected by their prices. The Mighty is a serious cutting machine but with some compromises like slower tool change, slower rapids, fewer control features, etc.

Some things to consider:
- How many parts do you need to run?
- Is this production work? What sort of quantities?
- What kind of cycle times?
- How will the large workpieces be loaded?

For example, do you need to put a couple holes in thousands of parts each day? Then tool change and part loading will have a huge effect on throughput. One piece with a thousand holes each day means tool change and part loading are of lesser concern than frequent loading/unloading and tool changes.

[schurches]

We are a job shop so the parts will vary for all the criteria you mentioned. Cycle time and tool change time are not major issues for us. Making good parts consistently is the key for my shop.

[DareBee]

Originally Posted by schurches We are a job shop so the parts will vary for all the criteria you mentioned. Cycle time and tool change time are not major issues for us. Making good parts consistently is the key for my shop.

I disagree

I am a job shop, and I am often slow in the machining department but for drilling and tapping you will be very unhappy (in the long run) with a slow tool change.
You get into 3 or 4 diff size tapped holes and 2 milled pockets in a piece and need to make 10 pcs.
Equals 14 tool changes (my Fadal 10-16 sec/change) = 4 minutes per part on a 12 - 20 minute job = 20to35% per part.
If you have competition in your market this can really start to hurt the bottom line after awhile.

Cycle times you can usually fine tune but anything less than 400IPM rapids will also be VERY costly and 400 is even too slow.

On the other hand the difference between doing these jobs on a VMC and doing them on a conventional mill is night and day for simplicity and speed. If you pick up a vmc dirt cheap you can justify a slow unit, but to buy a NEW one that is slow is NOT the way to go and you will regret it.