Newbie- What cnc machine to use?

[LoganM]

Hi,
I just started making camping products and I'm trying to make a camp stove and I have no idea where should I take my design.

Would a laser cnc will be overkill and I should use a normal cnc machine or laser is the best way to go? Or should I choose something completely different?

After looking around a bit I thought it would be best to take advice

it will be made out of 4 pieces of 15cm x 21cm stainless steel (0.6mm) which will have 5mm screw holes, 2mm x 1cm cuts and vent holes with 3cm diameter on it. Also a writing if possible.

I'll be happy if you can share your thoughts.

[Ed from NY]

I would prototype in 1/16" aluminum by hand and then use a local shop to have a few variations in your target material (stainless steel 0.6mm) water jetted.

After you are set on the design and are satisfied that it works well in the field I would look to have it stamped.

EDIT: If you are more of a computer type you can do the prototype digitally (Autodesk, the makers of AutoCad, have offerings in that area). From there you could go directly into the water jetted variations.

[LoganM]

Thank you for the reply,
I already made one with hand and made changes on it. Then I drew it with AutoCAD. so I already have the design.

There are two concerns now, what stainless steel should I use and what to cut it with.

Before reading your answer I gone to a few places and they sad it could be only done with Laser CNC. No one even mentioned stamping. and some of them told 5 times higher prices then others for Laser cutting which I didn't understand.

Is there quality differences between cnc lasers which will result in 5 times higher prices?

[GrandLordKhorne]

Stainless wise, for camp stoves, 316 or 321 would probably be best. I have had backpack stoves made out of both. 321 is a little better than the 316 but 316 was fine.

Price is often heavily affected by what the shop normally produces (basically there capabilities) and how many you order. To some extent that hast to do with weather they have a big machine that makes your part easily or a small machine that works closer to its limits to make the part. Which effects how fast they produce a part, slower production means higher machine time which means higher cost. A little bit of the variation is quality. Having said that, I tend not to trust anyone who tells me that there is only 1 process to make a part. Also, most backpack stoves are stamped because it is significantly cheaper than CNC to produce.

Just my two cents…

[LoganM]

Thanks for the reply GrandLordKhorne,
Then I'll look into stamping too. Does stamping leave any residue or bend the edges around the cuts and holes? 'cause I'm going for quality as well as price

[GrandLordKhorne]

A good sharp die set leaves crisp edges and good quality. I don’t have a lot of experience with small parts stamping but the dies in an automotive plant get touched up every few thousand strikes and can last for as much as 3 million cycles. Most of the dies I have personal experience with make parts that a team of average people could not pick up on there own. The big thing to look for in stamping operations is a die maker with experience making parts of the size and complexity similar to what you want to make. There is a sort of art to the whole process, some one who is good at making car doors for instance may not necessarily be good at making washers and visa versa.

[Crispymetal-fab]

My two cents in...

The biggest thing to consider when deciding whether to stamp your assembly or not is how many units do you plan to produce. The initial starting cost for stamping could make you $h!t your pants and or have a heart attack. Once tooling is made and proven, then your stamp shop could punch out your units at a price per part that you can live with. It's all in how many parts can you afford to run at per lot order. You want 10,000 parts? Then stamping is defintly a manufacturing method to concider. Anything less than that then you will want to really think if buying the stamp tooling is truely cost effective.

My recommendation would be to have a local job shop to qoute your product. Have at least three shops quote it for you to really get a idea. Have them give you a tour of there shop so you can see first hand the quality they can produce and not just some sample parts in the office.

Since most shops will quote your job by how long it takes to proccess through there shop, you may want to also consider letting your parts be punched. Turret punch presses are the fastest and cheapest way to get your parts blanked out and ready for the press brake to bend it up. A good shop will have nice sharp punches with the correct clearents to give a great looking part.

My shop has both a 2000w laser and a 30 ton turret punch press. Our deciding factor for which one to use is which one will get it done faster. For a part that thin and out 316ss, the laser might be best. If there are quite a few holes to put in it then the punch would be the way to go as there is no pierce.

This is getting quite long so I will stop now and let other replys in.

Thanks,
Curt

[LoganM]

Thanks GrandLordKhorne,
I guess the best thing to do is order 1 piece each from laser and stamp from different shops and then decide what to do. And I'll go with 0,6mm thick 321ss by the way. Thanks on that regard as well

Thanks Curt,
It’s a little early for me to buy my own stamping machine that’s for sure...
My consideration in time consumption is the edges more than holes for laser. It’s a 15cm by 21cm piece with 8 screw holes. It will be cut out of 2m*1m sheets. It wouldn't be a problem for stamping but for laser am I wrong?

[GrandLordKhorne]

^ What Curt is referring to is not the cost of buying stamping machines. It is the cost of having dies made. And he is actually right in a lot of respects. The cost of a set of production dies by themselves is astronomical. But for service life you can’t beat the cost of a stamping. In the end a stamped part can be pennies compared to a laser cut one when you amortize the cost across the life of the dies. Having said that, if you are producing a test die only it can be relatively cheap. For instance, if it was me, considering you are making parts from .6mm (aprox 24ga) stainless, I would make a set of dies out of plain old O1 tool steel that would punch 1 part at a time and run them in a simple piston press with graphite lubricant. I would expect such a set to last a couple hundred parts and if the product took off I would build a set of production dies that struck the max number at a time from full size sheets. The first few parts would be relatively expensive because the dies only make 1 at a time and it would be slower than production stamping, but the cost would be much easier to bear than a full set of production dies.

Interesting side note: I have made test dies out of fiberglass before. We tried them because we wanted to make 5 parts or so to see weather or not what we where up to made any sense. Initially we where going to be happy if we could get 1 or maybe 2 parts. In the end the composite dies made 33 acceptable parts before they became useless. We where stamping in 14ga low carbon steel into parts about the size of car hoods.

[Crispymetal-fab]

Oh no no.. lol, sorry I didnt mean for you to buy your own stamp machine. You will be paying for the tooling to be made, at which ever stamp shop you choose. That is what I mean by you going in your pants when you see that quote. Any good local precision sheet metal job shop should be able to produce a product to your specs and quality that you are looking for at no where near the costs of a stamp. One of my shop best customers is a stamp shop out of Denver. When they need prototypes, or their customer has a new part but won't order the quantity to justify making the tooling, they contract us to produce it for them.

Most laser metal cutting machines can easly cut through .6mm stainless. Our shops laser is 2000w of power and we have cut up to .250inch stainless.

Lasers have their purpose and can produce great parts, but a turret punch can do great as well.

Lets say this was at our shop, and first you order five or so units out of .024" stainless.(.6mm) We would most likely laser it as there is no set up time. If more than five or so units, we would probably quote it for our turret punch as it would help your quote stay low. For that thin of stainless, your edge quality would be pretty good no matter what method you and your supplier choose as long as their operator and inspector do a good job.

[Crispymetal-fab]

ha ha, was writing that last reply and GrandLordKhorne was able to post first. Yes, Production Stamping dies will give a heck of lot of parts for a heck of a lot cheaper, if you buy enough parts to offset the tooling.

I must admit, never thought of using fiberglass for test dies. Intresting concept...

I still belive having your parts made at a fab shop should be cheaper, at least untill your quanitys get to the point where production stamping is more cost effictive. We have quoted against some machine shops making test dies and for the quanitys that those dies produce, we were still cheaper and faster in lead time.

curt

[GrandLordKhorne]

I completely agree that for small quantities you can’t beat a fab shop. I tend to be a little bias to traditional methods, but I grew up in a family that dose things that way. I suppose the real answer would be how many units do you intend to produce and over what time period. Than at what point dose a set of dies pay for it’s self and at what point dose stamping become faster. Really the thing to do is to sit down with several possible makers and talk these points over.

If you are slightly insane like I am, you could whip out your tools build your own press and dies, build your own laser and then compare the two and fined a new application for the one that dose not do it for you…




Composite dies where an interesting foray into something untried. We did them because they where cheap, they where built in a day and by our calculation they could make the one prototype panel we needed. Construction wise, they where S-glass and Epoxy made over a clay mold and vacuum bagged.

I would really love to post photos of the composite test dies but they made a military proprietary part and as such I can’t show them off. Having said that, all threads are better with some sort of photo. So here is a pic of one of the 50,000 ton forging presses I worked with. Dies for this sucker typically weight 100 tons for a set. This press is typically used for single strike forging of titanium into things like aircraft bulkheads. Interestingly enough, the press was originally German and dates back to the WW2 era. The photo really dose little justice to it’s true size and beyond what you see, it extended 3 stories into the ground.