There is a moment in every growing manufacturer’s story where a single machine stops being a machine and starts being the whole production line’s bottleneck. It usually announces itself quietly: parts pile up in front of one operation, and the rest of the shop waits.
The customer in this story made small round components — the kind of precision parts that end up in fuel systems and fluid-handling equipment. Their bottleneck was a deep hole drilling step: a Ø2mm hole, 120mm deep, in every single part they shipped. The hole was tiny, but it was deep, and drilling it one at a time on a single-spindle gun drilling machine took longer than every other operation on the part combined.
Then their order volume doubled. And the math stopped working.
The Problem: Adding Machines Isn’t Scaling
The obvious answer to a bottleneck is to buy another machine. And a second single-spindle gun drill would have worked — barely. But the customer looked at the numbers and realized what we see all the time:
- Each single-spindle machine needed an operator. Two machines, two operators.
- Each machine took up floor space, consumed power, and duplicated tooling inventory.
- And the real problem: one spindle drills one hole per cycle. Doubling machines only doubled the holes per minute if every machine ran with a dedicated operator around the clock — which nobody does.
The bottleneck wasn’t a horsepower problem. It was a parallelism problem: the customer needed four holes drilled in the time they were drilling one, without multiplying labor and floor space.
The Answer: Let Four Spindles Work at Once
This is the case for multi-spindle gun drilling. Instead of one spindle cutting one hole per cycle, a multi-spindle machine runs two, four, or six spindles simultaneously — each drilling its own part in the same cycle time as a single hole.
For this customer, the numbers were stark:
- Same cycle time, four times the output. Four spindles, four parts, one cycle. Throughput rose to four times without a single second being shaved off the cutting process.
- One operator, not four. The machine loads and unloads all four spindles from one station. Labor per part collapsed.
- A fraction of the floor space. One multi-spindle machine replaced the footprint of several single-spindle machines.
- No compromise on the hole. Each spindle still drills with the same gun drilling precision — straightness, diameter, and finish unchanged.
The specific machine was from our RD-S multi-spindle series, which is built for exactly these small-round-part jobs: Ø1–6mm holes up to 500mm deep, four spindles running simultaneously. It was a match for this customer’s Ø2mm × 120mm part the way a custom-tuned setup is meant to be.
The Engineering: It’s Not Just More Spindles
Bolting extra spindles onto a machine doesn’t automatically deliver four times the production. The value is in how they work together, and this is where the engineering detail lives:
- Independent depth control. Each spindle can drill to its own depth within the same cycle. Not every part in a batch is identical, and the machine doesn’t have to average them.
- A fixture that loads four parts at once. The workholding was designed so the operator (or the auto-loading system) positions all four parts in one motion, not four separate ones.
- Synchronized parameters. All four spindles run the same proven process — the same feed, speed, and coolant — so quality is uniform across the batch, part 1 to part 4000.
- A centralized coolant system. One high-pressure system feeds all four spindles, with filtration that keeps every cutting edge in clean fluid.
We cut trial parts on four spindles at once before anything shipped. The acceptance test was simple: four identical holes, four identical parts, in one cycle time, at the quality the customer’s own inspection required.
The Result
The customer’s bottleneck disappeared:
- Throughput rose fourfold on the same floor, with the same number of operators.
- Unit cost per hole dropped, because labor, power, and floor space were now spread across four times the output.
- The line stopped waiting. The deep hole step, previously the slowest, became just another operation — and when their volume doubles again, there is headroom in the machine, not a panic.
The part they make is unchanged. The hole is unchanged. What changed is the answer to the question every manufacturer eventually faces: how do I make more without making it cost more?
When to Consider Multi-Spindle
A multi-spindle machine is not for everyone. It earns its keep when your situation looks like this:
- Small, repetitive parts — where every part needs the same hole drilled the same way.
- A drilling step that dominates the line — the hole takes long enough that every other operation ends up waiting on it.
- Rising volume — you are adding output, not replacing a failing machine.
- Labor and floor space are the real constraints — the thing you can’t easily add is people and square meters.
If your production is at the point where “buy another machine” feels wrong but the demand is real, talk to us about your numbers — part size, hole spec, and volume. We will tell you honestly whether multi-spindle is the right answer, or whether a different configuration fits your parts better. The goal is never to sell you more spindles. It is to make your bottleneck go away.