A step-by-step framework for engineers and procurement managers evaluating rotary transfer machines. Covers the 5 critical decisions, common mistakes, and a supplier evaluation worksheet.
Rotary transfer machines are significant capital investments — a typical RTM costs between $150,000 and $500,000 and will run in your facility for 15–20 years. Choosing the right configuration at the purchase stage prevents costly problems down the line: bottlenecks from insufficient stations, quality issues from inadequate fixture rigidity, and production losses from unavailability of spare parts.
This guide walks through the 5 decisions that matter most when selecting an RTM.
Before looking at any machine, map your part families. How many different part types will this machine run? What are the bore sizes? How many machining operations does each part require (drill, tap, ream, bore, face, thread)?
If single high-volume part: Optimize the station configuration for that part's exact operations. Maximum efficiency.
If multiple part families: Design the fixture system for quick changeover (30–60 minutes). Consider the 8-station configuration for flexibility.
The number of stations determines how many operations happen simultaneously and how many operations are queued at any given time.
| Stations | Best For | Cycle Time Range |
|---|---|---|
| 8 stations | High mix, smaller batches, simpler parts (4–6 operations) | 5–10s/piece |
| 10 stations | Valve bodies, compressor cylinders, typical industrial parts (6–8 operations) | 3.5–7s/piece |
| 12 stations | Complex parts with 8–10+ operations, large bore sizes | 6–12s/piece |
Your required pieces-per-hour drives the entire machine specification. Calculate: (Required annual volume ÷ operating hours per year) = required UPH (units per hour).
Then work backward: if you need 500 pieces/hour and each station takes 4 seconds for its operation, you can determine the minimum number of stations needed. Most standard valve bodies achieve 3.5–7s/cycle on a 10-station RTM.
Siemens 828D is the industry standard for rotary transfer machines globally — it has the largest base of service engineers and the most mature post-processing support. FANUC 0i-MF is the primary alternative.
Key questions: Does your maintenance team have existing Siemens or FANUC experience? Is there a local FANUC or Siemens service presence in your region? What is the remote diagnostics capability?
Both systems support ISO G-code, macro programming, and tool data management. The programming interface differs but the capability is equivalent.
The machine will run for 15–20 years. The supplier's service infrastructure matters more than the machine specification at year 5, 10, and 15.
Evaluate: Does the supplier have a local service engineer in your country? Where is the nearest spare parts warehouse, and what is the dispatch time? Is 7×24h remote diagnostics included in the standard warranty? Can you speak directly with an application engineer — not just a distributor — when you have a process problem?
Use this checklist when evaluating any RTM supplier, regardless of origin:
Can they run your actual parts at their facility? Request video documentation of cycle time, chip form, and surface finish.
What brands of spindle, guide rails, ball screws, and control system? All should be recognizable international names.
ISO 9001 minimum. CE marking for European market. Request copies of certificates.
From your location — what is the realistic parts dispatch time? Ask specifically, not generically.
Is there a named service engineer who speaks your language and knows your region? Or just a distributor who escalates?
Can the supplier connect to your machine remotely for diagnostics? Is this included in the warranty or an extra-cost option?
Can they provide 3 customer references in your industry (valve, automotive, compressor) in your region?
Get the lead time in writing. A typical range is 3–6 months for Chinese manufacturers, 8–16 months for European manufacturers.
Most DN15–DN50 ball valve bodies are optimally run on a 10-station RTM. This allows 2–4 stations for port operations (boring, reaming, rigid tapping), 1–2 stations for face machining, 1 station for threading, 1 station for deburring/inspection, and 2–3 stations as buffer or for additional operations. DN50–DN100 valve bodies may require 12 stations depending on the number of ports and thread sizes.
For typical valve body and compressor cylinder applications: 3.5–10 seconds per piece depending on part complexity and station configuration. Simpler parts with fewer operations can achieve faster cycle times. Complex parts with deep bores or many operations will be at the slower end. The only reliable way to establish achievable cycle time for your part is a FAT at the supplier's facility.
For rotary transfer applications, both are equivalently capable. Siemens 828D is the industry standard and has the broadest base of service engineers globally. If your maintenance team has existing FANUC experience, FANUC 0i-MF is a perfectly valid alternative. The choice should be driven by your team's familiarity and the local service infrastructure for each brand in your region.
Use the same evaluation criteria regardless of origin: component brands, quality certifications, FAT capability, spare parts lead time from your region, and customer references in your industry. Reputable Chinese manufacturers like APEX use the same international component brands (Siemens, SKF, Rexroth) as European builders. See our full comparison: China vs Europe CNC Machines.
Upload your part drawings. Our engineering team will recommend the optimal RTM configuration — station count, tooling plan, cycle time estimate — and provide a formal quotation. No commitment required.
Engineering response within 24 hours. FAT available before order.