Swiss-Type CNC · Stainless Steel
Reducing a SUS420J2 Thin-Wall Part Cycle from 10 to 8 Minutes on a STAR SP-23
OUJI machined this 1,000-part SUS420J2 job in the annealed condition, kept an approved anonymized 17.3 ± 0.02 mm feature within limits on the documented optical check, and stabilized the machining cycle at 8 minutes per part after an initial 10-minute cycle.
At a Glance
- Material
- SUS420J2 stainless steel, machined in the annealed condition
- Process
- All cutting operations and the S2 marking completed within the SP-23
- Machine
- STAR SP-23 Swiss-type automatic lathe
- Production volume
- 1,000 parts
- Public critical dimension
- 17.3 ± 0.02 mm; documented optical reading: 17.310 mm
- Machining cycle
- Stable at 8 minutes per part, reduced from the initial 10 minutes
- Final hardness requirement
- Nominal HV600 after post-machining heat treatment
From the Production Drawing
The Requirement, in the Engineer's Own Notes
The published excerpt retains the irregular thin-wall geometry and replaces the customer dimension with the approved anonymized public value of 17.3 ± 0.02 mm. Customer identity, part number, title block, approvals and all other dimensions are removed from the image pixels. The public value is used only to explain the machining and inspection method.
01
The Challenge
The engineering risk came from the combination of requirements rather than one isolated tolerance. The SUS420J2 was cut in the annealed condition, but the part still combines an irregular thin-wall ring, an interrupted internal cross feature and an S2 marking. Those discontinuous, lightly supported sections can be sensitive to cutting force, heat, burr formation and distortion while the approved anonymized 17.3 ± 0.02 mm feature still has to be controlled. The drawing also calls for post-machining heat treatment to a nominal HV600, so the hardened end condition had to remain a downstream requirement rather than being confused with the material condition during cutting. At 1,000 pieces, the useful target was a repeatable production cycle, not one unusually fast first-off part.
02
OUJI's Approach
OUJI completed every cutting operation and the S2 marking within the STAR SP-23, without moving the part to a secondary machine. This defines the machining scope only: heat treatment and dimensional inspection remained separate downstream stages. The initial route ran at approximately 10 minutes per part. Engineers then optimized the machining method and feed rates, balancing the time reduction against stable cutting around the thin wall. The production cycle settled at 8 minutes per part.
03
The Result
The stable machining cycle fell from 10 to 8 minutes per part, a 20% reduction. Comparing the two rates across 1,000 pieces gives a calculated machining-time reduction of 2,000 minutes, or 33 hours 20 minutes; this is a rate-based comparison, not a claim that all 1,000 parts first ran at the slower setting. The approved anonymized dimension of 17.3 ± 0.02 mm defines an acceptance range of 17.280–17.320 mm. The photographed KEYENCE optical check reads 17.310 mm, which is 0.010 mm above nominal and 0.010 mm below the upper limit. That image documents one measured feature on one inspected part. It does not by itself establish batch-wide capability, Cpk or a zero-defect result. The nominal HV600 value is reported as the specified final hardness after heat treatment because the published image set does not include a hardness-test record.
Production Sequence
From Thin-Wall Process Planning to a Documented Optical Check
The production sequence separates what happened inside the SP-23 from the later heat-treatment and inspection stages, then connects the cycle-time change to a visible dimensional result.
Project facts on this page come from the production route and photographed inspection record. Customer-identifying information and all other dimensions have been removed. “Completed within the SP-23” refers only to cutting and S2 marking on that machine; it does not include heat treatment or inspection.
01 · Process planning
Treat the thin wall, cross feature and marking as one route
The two finished faces show why the operations could not be planned independently: the narrow annular wall, internal cross feature and S2 marking occupy the same compact component. The route was organized around their combined effect on support, burr control and dimensional stability rather than around a single headline tolerance.
02 · SP-23 machining
Complete the cutting operations and S2 marking within one machine route
All cutting operations and the S2 marking were completed within the STAR SP-23, without moving the part to a secondary machine. Heat treatment and inspection followed outside the machine and are not included in that one-machine scope.
03 · Cycle optimization
Tune the machining method and feed rates against the part, not the stopwatch
The initial route took approximately 10 minutes per part. Engineers optimized the machining method and feed rates, balancing shorter cutting time against stable production around the thin wall. The resulting 8-minute cycle is the stable production rate reported for this 1,000-part job; proprietary parameter values are intentionally not presented as universal settings.
04 · Optical verification
Compare the 17.310 mm reading with the public tolerance limits
For the redacted 17.3 ± 0.02 mm feature, the lower and upper limits are 17.280 mm and 17.320 mm. The photographed KEYENCE screen records 17.310 mm, placing this checked feature inside that range. The page keeps this as a single documented result and does not extend it into an unsupported batch-capability claim.
Sources & technical references
- SP-20/23 Swiss-type automatic lathe — Star Micronics Co., Ltd.
Manufacturer reference for the SP-23 machine platform used in this project. Project-specific setup and cycle-time values come from OUJI production records.
- LM-X Series multisensor measurement system — KEYENCE Corporation of America
Manufacturer reference for the optical measurement system shown in the inspection photograph. The 17.310 mm result comes from the photographed project record.
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