A robotics manufacturer in Hanover, Germany working in robotics and automation has an aluminium joint housing whose bearing bore, shoulder and dowel holes must survive deburring intact. SurfacePolish supplies finishing machines, media and compounds across borders and runs a free sample trial: representative parts travel to the factory in Xiamen and come back with observations and a proposed media, compound and cycle direction for the buyer's own review. This brief is written for a buyer in Hanover 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?
Which surfaces on the part are functional, such as bearing bores, dowel holes, seal lands, ground mounting faces and threads, and which are only cosmetic?
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?
Batch composition is a process variable. Mixing aluminium and stainless parts in one charge spreads aluminium fines onto the stainless and leaves a dull grey film; leaving small steel fasteners loose among aluminium housings produces impact marks and ferrous contamination. Decide the mix, the maximum mass per batch and whether delicate parts need compartments. Decide as well how a batch is identified, with a traveller carrying part numbers, alloy, machine, media charge, compound, cycle time and inspection result, so a finished lot can be traced back to the settings that produced it. Then record honestly what the parts arrived with, because cutting oil, coolant, machining chips, a previous blasting residue or a handling scratch all change what one cycle can achieve and are easy to attribute to the wrong cause later.
Disc finishing machines and centrifugal barrel machines deliver far more energy per unit of time than a bowl. A disc machine works the gap between rotating discs, which suits batches of small robust parts such as gripper jaws, mounting blocks and machined brackets where a consistent edge break is wanted quickly. Centrifugal barrel finishing multiplies the effective gravity acting on the charge, so cycles shorten and contact pressure rises sharply, which suits small precise parts and can round a thin section or deform a soft aluminium wall within a short over-run. Both routes depend on charge weight, speed, fill level and stop time being held to a record. They are a poor match for thin-walled housings, long beams and any part whose functional edge or bore lip must keep a tight radius.
| Machine route | Where it fits | What it will not do |
|---|---|---|
| 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 |
| Disc finishing machine | Fast, high-energy edge breaking and surface refinement on small robust parts and uniform batches of gripper jaws, blocks and fittings | High impingement and edge-loss risk on thin, soft or aluminium parts, and the geometry must suit the disc working gap |
| Grinding finishing machine | Taking off a heavy machining burr, dross or a defined stock layer before a refinement pass on robust steel and stainless work | High removal energy cuts functional edges fast and demands a tighter assessment of what may be removed and how much |
| Centrifugal barrel finishing machine | Small precise parts and short cycles with high contact pressure, such as spools, small inserts and compact machined components | Rounds edges and can distort thin unsupported sections quickly; results are sensitive to charge weight, speed and stop time |
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 |
|---|---|---|
| Dry media such as walnut shell and corn cob | Drying assistance and light surface polish after a wet cycle, particularly on parts with pockets and threads that must not stay wet | Does not deburr or refine metal significantly, generates dust, and must not be treated as a cleanliness step |
| 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 |
| 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 |
| 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 |
Edge rounding beyond limit is the failure that most often turns a finished automation part into scrap, because the features that round first are the ones that set position. A bearing bore lip, a dowel hole edge, a seal groove corner or the edge of a ground mounting land can lose a fraction of its geometry under a high-energy charge and still look uniform and polished. Coarse or dense media, an over-long cycle and a heavy load ratio all accelerate it, and aluminium rounds faster than stainless under the same conditions. Because the damage is invisible to a casual look, checking has to be deliberate: measure the feature before and after with an optical comparator, a radius gauge or a moulded replica, and compare the result with the limit on the drawing. Masking, a shielding fixture or a gentler medium are the usual mitigations to test.
| Failure mode | Likely cause | How to catch it |
|---|---|---|
| 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 |
| Water spotting, mineral rings or haze left after wet processing and drying | Hard or high-chloride rinse water, slow or uneven drying, or parts stacked wet so moisture is trapped in pockets and threads | Inspect dried parts under angled light for rings and haze, check the rinse water source and the drying method, and confirm that pockets and tapped holes drain before packing |
| 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 |
| 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 |
Hanover is the capital of Lower Saxony and combines a large manufacturing plant with a trade-fair and logistics economy. Volkswagen Nutzfahrzeuge (Volkswagen Commercial Vehicles) is based at the Hanover site and describes itself as one of Lower Saxony's largest employers, which anchors a vehicle-industry supplier base in the region. The city's exhibition grounds host the HANNOVER MESSE, presented by the city as the world's largest industrial trade fair, with exhibitors from mechanical engineering, the electrical and digital industry and the energy sector, and its main display areas are automation and digitalisation, energy and industrial infrastructure, and research and technology transfer. Hanover's port group (Städtische Häfen Hannover) operates four ports on the Mittellandkanal and its branch canals, with the Lindener Hafen serving chemicals, mineral oil, forwarding, the vehicle industry, construction, recycling and steel trade, and the airport adds an air-freight centre with around 60,000 tonnes annual capacity. EuroBLECH, the international sheet-metal working technology fair, is also held on the Hanover exhibition grounds.
For this brief the relevant part of that base is automation: Automation and digitalisation is one of the three main display areas of the HANNOVER MESSE held on the Hanover exhibition grounds.
Hanover's production base is commercial-vehicle manufacturing with its supplier tier, steel trading and steel processing, and the sheet-metal working technology community that gathers at EuroBLECH on the city's exhibition grounds. Those processes - cutting, forming, punching, welding and machining of steel and sheet - are exactly where burrs, sharp edges and oxide or oil films must be removed before welding, coating or assembly. Because a large share of Hanover's metalworking demand is job-shop and supplier production rather than one dominant end product, finishing choices usually have to cover a mixed part spectrum in one installation.
Because Hanover's metalworking base is broad and supplier-driven, the first question is which part spectrum and edge/cleanliness standard one installation must cover (for example EN 1090 steel construction edges versus VDA 19.1 cleanliness for vehicle parts), and whether the process must be reproducible across mixed batch sizes rather than optimised for a single part.
Freight context: Hannover Airport (HAJ) with its air-freight centre, Hafen Hannover: Lindener Hafen, Nordhafen with the Container Terminal Hannover, and the Rail Terminal Hannover-Leinetor, Mittellandkanal / Stichkanal connections and the Hanover motorway junction (A2/A7). The port operates two combined-transport facilities with services to northern Italy and the German North Sea ports, so seaborne containers destined for Hanover can be handled inland rather than only at the coast, and Hannover Airport adds an air-freight centre with around 60,000 tonnes annual capacity. For incoming finishing machines and sample parts, Hanover offers inland-waterway/rail container handling, road freight on the A2/A7 and air freight at HAJ.
Machinery placed on the German market must be CE marked, and the manufacturer is responsible for the conformity assessment, the technical file, the EU declaration of conformity and for affixing the mark; importers and distributors are separately obliged to ensure that only compliant, CE-marked products are placed on the EEA market (c3, c4). The customs authority is German customs (Zoll), part of the Generalzolldirektion, and the operator identification it issues, the EORI number, is a prerequisite for customs clearance in the European Union (c5, c6). In general EU practice a buyer's landed-cost plan therefore needs to cover the commodity-code classification that sets the duty rate, import VAT and the customs declaration, on top of the CE technical file and an identified EU-based economic operator who can act as importer or authorised representative; the technical documentation and the declaration of conformity must be available in the language required by the buyer's market surveillance authority.
Germany sits inside the EU customs union, so Chinese-origin industrial machinery enters against the EU's common commercial tariff rather than a German national tariff, and the duty that applies is determined by the commodity code declared on the import declaration. China is one of the EU's largest goods trading partners and the EU has long run a goods deficit with it, while the Commission characterises the relationship as simultaneously partnership, competition and systemic rivalry (c1, c2). The Commission publishes the EU's trade agreements; no agreement with China appears in that overview, so Chinese-origin goods cannot claim a preferential origin rate and are assessed under the standard tariff (c8). German customs is administered by the Zoll under the Generalzolldirektion, and the importer must hold an EORI number - valid throughout the European Union and replacing the former German customs number - before goods can be cleared (c5, c6).
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.
Change one variable at a time. If the question is media shape, hold the machine, load, compound, cycle time and part mix constant and change only the medium. If the question is cycle time, hold the charge and settings constant and stop at two or three defined intervals. Use adjacent coupons or parts from the same production lot so the only difference is the variable under test. Label the pieces before they run and have the returned parts judged in one session under the same light, rather than one at a time as they arrive. Where several people judge appearance, ask each to rank the parts before discussion so the strongest opinion does not set the answer. Running two changes at once produces a result that cannot be attributed to either.
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.
They can, but not without a changeover discipline, because the failure is contamination rather than damage. Aluminium fines retained in media, compound or a machine sump transfer onto stainless as a dull grey smear, and iron from steel media or carbon steel work shows up on stainless as rust spotting that appears hours or days later. Practical controls are dedicated or segregated media charges, a purging routine for the machine and sump, a compound change where needed, and a record of when the changeover happened. Where the volumes justify it, separate machines or separate charges are simpler than a cleaning procedure. Only you can decide which arrangement is acceptable for your own contamination control.
Size the medium well below the smallest opening the charge could enter, and treat every passage as a retrieval point rather than assuming it stays clear. Map the tightest tapped hole, keyway or cross-drilling first, then choose a size class against that geometry instead of an average part. Add a defined check such as a pin or thread gauge on holes, a borescope at an agreed angle and a rinse collected through a filter. For a trial, send the part with the smallest opening so the media choice is tested on the real feature. SurfacePolish reports what was observed on the tested parts; the release decision remains with your own quality function in Germany.
Use Hanover, Germany 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.
Hanover buyers work within the DIN system: surface-texture specification to ISO 21920, technical cleanliness to VDA 19.1 / ISO 16232 where hydraulic or powertrain parts are involved, material certificates to EN 10204 (3.1), and for steel construction work the EN 1090 execution classes. Automotive suppliers operate to IATF 16949 with VDA 6.3, and machines placed on the EEA market must carry CE marking under the EU Machinery Regulation.
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 Hanover.
The buyer needs the milled edges broken and the external faces evened out without touching the bearing bore or closing a dowel hole.
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-0400; 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-0400 · revised 2026-09-29 · cross-border equipment, media and scoped sample review. City context is sourced and cited above.
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