A pneumatics maker in Yokohama, Japan working in robotics and automation has a stainless actuator body whose bore lip and port threads must not be rounded or galled by edge finishing. SurfacePolish supplies finishing machines, media and compounds across borders and runs a free sample trial: the part goes to Xiamen, is processed under recorded settings, and returns with observations and a proposed media, compound and cycle direction for the buyer to verify. This brief is written for a buyer in Yokohama working on robotics and automation; it describes equipment, media and a scoped sample review, not a local polishing service.
What is the size and mass spread inside one part family, and does one machine have to cover both a heavy casting and a small gripper jaw?
How much of the incoming contamination, cutting oil, machining chip and handling damage is expected to be removed by finishing rather than by an earlier operation?
What does the finishing step actually have to deliver before the next operation, whether that is assembly, anodising, painting or a functional test, and who defines that requirement?
Automation work mixes scales in a way that catches buyers out. The same shop may finish a 40 kg robot base casting and a 30 g gripper jaw, and a machine sized for the casting will over-work the jaw. Load ratio, the mass of parts against the mass of the charge, is the variable that usually decides whether small parts come out even or rounded. Screen the family on its extremes: the heaviest part, the largest envelope, the thinnest unsupported wall and the smallest part that must meet the same appearance. Long linear-axis beams and thin cover plates distort under their own weight in a deep bed, while heavy castings need a chamber large enough to keep them moving. A shortlist built on the average part will miss both ends of the range.
Steel media produces the brightest appearance of the common charges and the highest contact pressure, and it brings a contamination question with it. On aluminium it can embed iron-bearing fragments that show up later as rust spots or as particles in a wiped sample, so a shop that runs both materials needs a changeover discipline, dedicated charges or a different route for the aluminium work. Separation at unload matters as much as the choice: steel media is dense, retains in blind holes and slots, and can only be recovered magnetically if the equipment and the procedure are set up for it. The compound has to keep the charge clean and inhibit corrosion on the parts. A bright result from a steel charge is an observation about a surface, not evidence about cleanliness or fitness for a downstream process.
| Media | Best fit | Watch out for |
|---|---|---|
| Plastic cylinders and cones in a harder, denser grade | Longer cycles on mixed batches of small fittings and screw-machine parts where a repeatable light edge break is wanted without ceramic impact | Can float or segregate by shape in a bowl, and cylindrical forms can wedge in slots, keyways and cross-drillings |
| Magnetic finishing pins and fine magnetic media | Small precise items such as spools, orifice plates, small valve parts and fine slot arrays where tumbling media cannot reach the feature | Limited working envelope, pins lodge in the same fine features they are chosen to reach, and the surface signature differs from tumbling |
| Heavy-cut ceramic, angle-cut triangles in a coarse size class | Removing a substantial milled or turned burr from open external edges and pockets on steel and stainless automation parts before a refinement stage | Cuts functional edges and corners aggressively, leaves a coarse surface on aluminium, and lodges in slots whose width approaches the media section |
| Fine ceramic or porcelain shapes in a small size class | Edge blending and surface refinement after a cutting stage, and reaching tighter external geometry on machined housings and brackets | Small sizes enter and retain in tapped holes and fine slots, and media wear shrinks the charge so the finish drifts over its life |
Inside any machine, the way parts are carried decides whether the finish is even and the geometry survives. Parts left loose together nibble each other along contact lines and produce bright impact marks on visible faces. Cradles that follow a casting, compartments, dividers and clip-on carriers present the same face to the media on every part and protect machined lands. Load ratio matters as much: too many parts in the charge reduces circulation and leaves shielded pockets unworked, while too few allows parts to be thrown against the chamber wall. Build the arrangement around the most delicate and the heaviest part in the family rather than an average one. Where a buyer plans automated loading or transfer between operations, the fixture interface, the orientation and the pick points belong to the buyer's own engineering scope and are defined and verified on that side.
| Machine route | Where it fits | What it will not do |
|---|---|---|
| Barrel finishing machine, rotary barrel tumbling | Gentle deburring of small fragile parts and mixed batches of screw-machine components with a generous compound flow | Long cycles, no visibility while running, and internal features can collect media and compound that must be retrieved at unload |
| Dry polishing machine and dryer | Removing residual moisture after a wet cycle and reducing water spotting on aluminium and stainless surfaces with pockets and threads | A finishing step only; a dry part can still carry compound film, fines and media dust, so it is not a cleanliness release |
| Tub vibrator | Long parts such as linear-axis beams, manifolds and welded frames that cannot rotate in a bowl | Lower energy per unit area so heavy burrs take longer, and large tubs need floor space and a reliable part support method |
| Vibratory finishing machine, bowl type | General deburring and refinement of machined housings, plates and brackets that fit and can tumble without racking, with easy mid-cycle inspection | Continuous part-on-part contact and no access to deep internal passages; thin plates and finished mounting faces need separation |
Contamination failures are quiet and are often attributed to the wrong operation. Aluminium fines left in a machine, a charge or a sump transfer onto stainless parts as a grey smear in the next batch. Iron from steel media, from a machine that has held carbon steel or from a tool used on both transfers to stainless and shows as pinpoint rust spots that appear hours or days later. Hard or high-chloride rinse water and slow drying leave mineral rings and haze on aluminium. A compound that is too aggressive darkens aluminium or attacks a freshly cut edge. The controls are procedural: segregate or dedicate media by material family, define and record the changeover, control rinse water and drying, and inspect after a defined dwell time rather than immediately. Left unchecked, these defects surface after the parts have moved on.
| Failure mode | Likely cause | How to catch it |
|---|---|---|
| Uneven finish with unrefined pockets, internal corners or the shielded side of a flange | Media cannot reach the feature at the chosen size or orientation, charge circulation is blocked, or the part was never repositioned during the cycle | Inspect at defined locations rather than judging the whole part, photograph the same feature before and after, and measure roughness only at the surfaces the drawing controls |
| Impact marks, dents or a peened, rippled appearance on a visible aluminium face | Charge mass or load ratio too high, light parts left loose among heavy neighbours, or a soft alloy run on a route chosen for steel parts | Look for repeating mark patterns under angled light, compare a part run loose with the same part compartmentalised, and review the batch mix and load recorded for the lot |
| Colour change or darkening on an aluminium face after the cycle | Compound chemistry unsuitable for aluminium, no effective corrosion inhibitor, or a delay between finishing and drying | Compare the finished face with an unprocessed coupon of the same alloy under the agreed light, and review the compound product, dose and rinse sequence for the lot |
| Bearing bore, bore lip or dowel hole edge rounded past the drawing limit | High-energy route, over-long cycle, dense or coarse media, or a functional edge run without masking or a shielding fixture | Measure the defined edge feature before and after with an optical comparator, radius gauge or moulded replica, and compare it with the maximum radius on the drawing |
Yokohama combines a waterfront heavy-industry zone with a large base of small and medium manufacturers. The city lists eight separate industrial accumulation areas, including the Keihin coastal zone, which it calls a major industrial region representing the Greater Tokyo area, and LINKAI Yokohama Kanazawa, where more than 1,000 companies and offices are located. The city's investment material states that Yokohama has clusters of automotive and other manufacturing, IT and life-science industries, together with R&D bases of global companies, and that it ranks first among Japan's designated cities for both the number of academic and R&D institutions and the number of engineers and researchers. The port's designated zones are predominantly industrial: of a 2,936.8 ha waterfront district, 1,712.1 ha is classified as an industrial port zone.
The nearest part of that base to this brief is machinery: The city identifies eight industrial accumulation areas including the Keihin coastal zone and LINKAI Yokohama Kanazawa, where more than 1,000 companies and offices are located, and describes Yokohama as having manufacturing clusters.
Yokohama's manufacturing base mixes automotive and general machinery production, in which deburring and edge quality affect fit, fatigue life and coating adhesion, with life-science and R&D activity, where cleanliness and documented surface condition matter. A dense supplier base across eight accumulation areas means an incoming parts specification is likely to pass through several subcontractors, so a shared, measurable finish requirement reduces rework at hand-offs.
A Yokohama buyer sourcing from an eight-area supplier base should fix one measurable edge and surface specification for the whole chain and agree who inspects it, rather than letting each subcontractor apply its own visual standard.
Freight context: Port of Yokohama (横浜港) — piers including Minami-Honmoku, Honmoku, Daikoku and Osanbashi, Haneda Airport, about 24 minutes from Yokohama Station by the city's own access description. The Port of Yokohama has a 7,218.3 ha port area and a 2,936.8 ha waterfront district, of which 1,712.1 ha is an industrial port zone, so both break-bulk and container movements of machinery sit alongside industrial waterfront users. The city publishes the Yokohama Port Statistics Yearbook and fast-report series for throughput data used in freight planning.
Chinese industrial machinery entering Japan is classified under the Customs Tariff Law, whose harmonised schedule sets the classification and the General Rate; the Temporary Tariff Measures Law sets a Temporary Rate for certain products, and where the WTO rate or an EPA rate for the goods is lower, that lower rate is applied. The applied rate therefore depends on the exact commodity code, and on whether an economic partnership agreement covers the goods and their origin, so a landed-cost figure has to be confirmed against the specific machine before it is quoted. Japan Customs' monthly country table for August 2026 records exports to China of 1,809,133 million yen and imports from China of 2,361,239 million yen, the largest single-country line in the Asian table, with imports from China up 22.5 per cent year on year.
Documentation and technical communication are Japanese-language in practice: JISC states that the documents submitted for JIS certification-body accreditation must be written in Japanese, and drawings, inspection sheets and purchase specifications from Japanese buyers are normally issued in Japanese. Import declarations are filed in triplicate and importers commonly use licensed customs brokers, so the commercial invoice, packing list and origin documents must be complete and consistent with the declared commodity code. As general industry practice in Japan, industrial buyers qualify a supplier on documentation, quality-management evidence and a defined inspection standard before volume orders, and expect a named Japanese-speaking contact for technical and commercial follow-up.
SurfacePolish supplies from Xiamen, China. The buyer's own destination rules, conformity marking, tariff classification and documentation responsibilities stay with the buyer; confirm them against the authorities named above before ordering.
Roughness is only comparable when the measurement conditions are fixed. State the location by distance from a reference feature, the traverse direction relative to the machining or media marks, the cut-off and the evaluation length, then use the same conditions for the first article and for production checks. A reading taken along a bore axis and one taken around its circumference describe different surfaces. Curvature limits how a skid or shoe sits on the work, particularly in a small bore or on a narrow land, and a poorly seated pickup is not evidence. Take readings at several stations, because the ends of a part and the middle of a part often differ. Where visual appearance is what the customer sees, pair the number with a physical reference viewed at an agreed distance, since a surface can measure inside a band and still look wrong.
A trial can only be read against a documented starting point, so record the incoming condition before shipping. Photograph each critical feature at a fixed scale, measure roughness at marked locations with the instrument, cut-off and direction noted, check edge condition with a radius gauge or comparator, and record mass and critical dimensions. Note the as-received burr, existing scratches, cutting oil or coolant and the condition of any tapped hole. Keep one piece unprocessed as the baseline. When the parts come back, compare them against those records rather than against memory or photographs taken on a different day under different light. That pairing is also how the buyer distinguishes a change produced by the process from a feature the material already carried.
Yes. The offer is cross-border supply of finishing machines, media and compounds, together with a free sample trial and a scoped discussion of a finishing line concept. That means machine class, media and compound are considered as one question rather than three purchases, since a charge that suits one chamber may not suit another. The buyer keeps ownership of the part, the drawing and the acceptance criteria, and we do not verify the material, the upstream machining or the heat treatment. Bring the part family, the alloys, the size range and the features that must be protected into the discussion, along with the condition the parts arrive in.
A trial shows what a given machine, charge and setting did to the parts tested, which is useful evidence but not a sizing study. Machine size depends on the largest envelope and mass in the family, the smallest part that must meet the same appearance, the load ratio you intend to run, and how many stages the part needs. Those are planning questions that belong in a line-concept discussion alongside the trial result. A part tested on a small machine may behave differently in a larger chamber, and a part run in a full production load may come out differently from one run in a light trial batch. Record both the settings and the load.
Ask for a record that identifies what was done rather than one that asserts a result. A useful record lists the part numbers and quantities in the lot, the machine used, the media type and size class, the charge mass and its age since the last screen or top-up, the compound and dose, the rinse water source, the cycle time, any interruption, the inspection results and the lot disposition. Request the media and compound data sheets. Where aluminium and stainless are processed on the same site, ask for the changeover note covering media purge, machine cleaning and compound replacement. This is finishing process documentation, not a certificate of compliance.
Use Yokohama, Japan as the destination on the enquiry and state whether the deliverable is equipment, media and compound, a representative sample review or a line concept. A destination does not imply local stock, a local service point or a local delivery time.
Yokohama buyers reference JIS, maintained by the Japanese Industrial Standards Committee, with the mechanical engineering and ferrous materials divisions covering machined metal parts, and the JIS Mark scheme available for third-party product certification, including to foreign exporters. For finishing, the customer's drawing and incoming-inspection sheet define burr, edge and roughness acceptance.
Sources were retrieved on 2026-09-29 and describe the local industrial and trade context only. They do not evidence any SurfacePolish project, shipment, installation or service in Yokohama.
The buyer needs the external edges and port threads cleaned up while the bore and its lip keep the geometry the seal depends on.
Send the material, dimensions, approximate weight, batch quantity, the incoming condition and photographs of the difficult features. Mark which features must not be contacted by media and state how the result will be inspected. This form carries source reference PSEO-0840; quote it if you prefer an additional manual reference.
Open the SurfacePolish enquiry form Email a prepared enquiry
No price, lead time, certification or result is promised here. Confirm whether a sample trial is available for the specific part and what the trial can and cannot show.
Page PSEO-0840 · revised 2026-09-29 · cross-border equipment, media and scoped sample review. City context is sourced and cited above.
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