How to Choose Between CNC, DMLS, and IPG Photonics Fiber Lasers: A 7-Step Checklist

Seven years into custom manufacturing, I can tell you the difference between a clean order and a costly surprise. It starts with one question: which process should we use? Not 'which vendor has the best price.'

I've approved over 400 orders for laser cutting, CNC, and 3D printed parts. I've also watched about $15,000 of that budget turn into scrap. Some of that was supplier error. Most was my failure to ask the right questions before signing.

This checklist is for anyone choosing between high speed CNC machining services, additive manufacturing, or a laser system. Use it before you approve a quote. It won't make you a hero in a sales meeting. It will stop you from becoming a cautionary tale.

There's a reason this is a checklist and not a long philosophy chapter. When you're standing on a shop floor with a customer on the phone, you need a short list of questions to pull from. This is mine.

1. Know the Material, Not Just the Name

In March 2022, I got a request to quote a C103 additive manufacturing run. C103 is a niobium alloy used in rocket nozzles and hypersonic components. I knew enough to recognize the material, but not enough to ask what the part actually had to do.

I approved a standard DMLS build. The parts came back with microcracks. I still remember the vendor's photo: cracks you could see without a microscope. $3,200 gone, plus a two-week slip on the customer's prototype schedule.

The lesson was simple: 'C103' is a material name, not a process specification. Additive manufacturing of C103 needs careful control of thermal history and often a post-print step like hot isostatic pressing. Ask about application, heat treatment, and testing requirements before anyone starts a build.

2. SLS vs DMLS: Read the Acronyms Twice

SLS vs DMLS 3D printing is one of the most common mix-ups I see.

SLS is for polymer powders. DMLS is for metal powders. The word 'laser' appears in both, which creates a kind of short-circuit in the brain. Here's the thing: if you need a metal bracket for an engine bay, SLS will not get you there. If you need a low-cost functional prototype in nylon, DMLS is overkill.

I once approved an order for a 'metal part' and let the supplier talk me into a powder-bed process without checking whether it was SLS or DMLS (ugh). It came back as black nylon. The part actually fit perfectly, but it was useless for the temperature test. $900 of tuition.

If you're not sure which one you need, ask this: what would I do if this part got hot? If the answer is 'it's metal,' you want DMLS. If the answer is 'it shouldn't be metal anyway,' you may be looking at SLS for polymer replacement, not final production.

And one more thing: DMLS is not the same as SLM, though the machines can look similar. In most commercial conversations, DMLS and SLM both mean metal powder bed fusion. Don't get lost in acronym details; get the material spec in the PO.

3. Ask Whether CNC Can Do It First

It's tempting to skip ahead to 3D printing for complex geometry. But in Q4 2024, we quoted a bracket with internal coolant channels and 5-axis machining came in 30% below the DMLS quote. High speed CNC machining services today can hold tolerances and produce surface finishes that additive processes can't match.

DMLS is not a magic wand. It shines when you have truly internal channels, lattice structures, or a one-piece assembly that would otherwise require welding. But for most parts, subtractive machining is faster and cheaper.

The industry is evolving. Five years ago, many shops pushed complex designs toward AM because machines couldn't reach those features. Now, with high-speed spindles and automated probing, the balance has shifted.

Another reason to ask CNC first: speed. We've had a high speed CNC machining services supplier turn around a batch of 50 aluminium parts in two days. The same geometry by DMLS would have taken six days just for the build, plus support removal and surface finishing. Lead time matters more than the cool factor.

4. The IPG Photonics Logo Is a Credit, Not a Guarantee

Walk through a modern fabrication shop and you'll see the IPG Photonics logo on laser cabinets everywhere. There's a reason for that. According to IPG Photonics (ipgphotonics.com), fiber lasers use a flexible fiber optic cable to deliver the beam to the workpiece. That makes robotic integration and beam switching much simpler than free-space optics. The company also highlights high electrical efficiency and low maintenance as practical advantages.

But the logo doesn't do the welding.

I once compared two 5kW systems for aluminium welding. Both used IPG Photonics fiber lasers. One produced clean, deep welds. The other was porous and weak. The difference wasn't the laser source; it was the weld head, focal position, wire feed, and shielding gas. The beam is only part of the system.

If a router or automation drawing says 'brand: ipg-photonics', that tells you the company made the oscillator. It doesn't tell you whether the machine can handle your part. Do not buy on badge alone.

The IPG Photonics logo on a machine cabinet is actually a good sign: the company has shipped thousands of industrial fiber lasers for cutting, welding, marking, and medical applications. But an oscillator is a component. The machine builder has to handle cooling, beam delivery, gas flow, and motion control.

I have a personal rule now: if someone hands me a datasheet with the laser brand circled, I ask to see the process qualification report instead.

5. Test on Your Actual Material

Before the $48,000 machine purchase in Q3 2024, we spent $200 on test coupons. The cheaper system failed to hold edge quality on 3mm aluminium. The system with the IPG laser source passed the bend test.

So glad we did that test. I was one signature away from approving the cheaper machine based on a spec sheet.

Test coupons don't have to be elaborate. Get the material, run the process, then cut, bend, and look at the cross-section. This applies to DMLS, SLS, CNC, and laser welding. If a vendor refuses to do a test coupon, that's a red flag.

If the vendor asks what 'good' looks like, write a pass/fail criterion before the test. For our aluminium project, 'good' meant no visible cracks at 3x magnification, full penetration, and no porosity on the bend radius. That sounds obvious, but it's the difference between a useful test and a vague exercise.

6. Price the Whole Cell, Not Just the Machine

In our last laser purchase, we got three quotes for nearly identical performance. The spread was about 40%. The cheapest quote excluded installation, training, and the first set of consumables. The most expensive included everything.

Ask about maintenance and consumables. IPG fiber lasers are generally lower maintenance than older lamp-pumped systems, but they are not zero maintenance. Coolant quality, protective windows, nozzles, and optics all wear. Anyone who tells you 'zero maintenance' is selling something.

Set-up cost can hide in surprising places. We had a quote that listed 'process development' as a line item, which is fair for new alloys like C103. But it wasn't in the original verbal quote. Get every line item in writing, including powder handling, support removal, heat treatment, and inspection.

Get the complete cost in writing.

7. Write the Requirement Into the PO

The last step is boring but powerful: put the part function, tolerance, surface finish, heat treatment, and test requirements into the purchase order.

When a vendor runs a DFM review and recommends a different approach, listen. If they say 'CNC will be more cost-effective at 200 pieces,' they're giving you useful information. If they say 'DMLS is not required for this geometry,' trust the data.

A Few Mistakes I Still See

These mistakes are not from suppliers with bad intent. They are from people who were in a hurry.

• Mistaking SLS for DMLS and ending up with a polymer part that can't take heat.
• Asking for C103 additive manufacturing without specifying thermal treatment requirements.
• Comparing laser prices by peak power instead of beam quality and system integration.
• Believing that a brand name like IPG Photonics equals a ready-to-run process.

The Basics Haven't Changed

As of early 2025, the market gives you a lot of choices: high speed CNC machining services, powder bed fusion, and fiber lasers integrated into robot cells. The vendors will happily sell you all of them. My job is to make sure you buy the right one.

What was best practice in 2020 may not apply in 2025. New materials, faster CNCs, better fiber lasers, and more mature additive processes are all changing the choices you can make. But the fundamentals are the same: know what the part needs to do, test your material, check the whole system, and get the details in writing.

It took me six years and a pile of scrap to understand that the process is not the goal. The part is the goal.

Take it from someone who paid for this checklist with real money. Use it, and maybe you won't have to.