1.5mm 440C G10 stainless steel ball

Product Overview

A 1.5 mm ball that sets the tolerance of the whole assembly

At 1.5 mm across, this is the smallest size we produce, and at that scale the ball decides how well a miniature mechanism runs. Each one is machined from 440C stainless steel, hardened to HRC 58–62 and ground to grade G10, so it arrives round, clean and consistent enough to go straight onto a line rather than into a re-work bin. Instrument builders, miniature bearing assemblers and repair counters order it by the ten thousand for that reason: a stainless steel ball sitting outside its grade is the fastest way to lose a whole batch of assemblies.

Nothing on this part is decorative. It works as a rolling element, a seat or a check ball inside small pumps, valve trim, aerosol mechanisms and instrument linkages, where it has to repeat the same movement thousands of times without changing shape. Set it beside a carbon or chrome small steel ball and the difference is the material: 440C gives up a few points of hardness in exchange for corrosion resistance that matters wherever condensation, cleaning cycles or the product itself brings moisture to the part.

The surface you receive is ground, clean and dry, with no oil film to wash off before assembly. That matters more at 1.5 mm than at any other size, because a film that is invisible on a 10 mm ball is a handling problem on a part this small.

Specifications

440C Material & Hardness

440C is a high-carbon martensitic stainless steel, which is why this ball can be hard and corrosion resistant at the same time. The grade hardens through heat treatment rather than through a coating, so the hardness runs right through the part and the ball you fit is the same material at the core. In practice that gives a stainless steel ball that holds its dimensions under load and still shrugs off damp workshop air, cutting-fluid mist and the rinse water that follows a wash-down.

The trade-off sits in the hardness number. A 100Cr6 bearing steel ball of the same size is usually specified a few points harder, in the HRC 60–66 band, and that extra hardness earns its place in a heavily loaded, well-lubricated bearing where corrosion is not a factor. Where the duty mixes load with moisture — pump internals, valve trim, instrument linkages that see cleaning cycles — 440C is the more practical choice, because a corroded race fails long before a slightly softer one wears out.

This grade is not a universal stainless. Standing chlorides, strong acids and marine exposure will attack it, and that is where a 316 ball belongs instead. If you are unsure what the medium will do to the part, send us the fluid and the duty cycle and we will tell you plainly whether 440C or a 316 ball is the better fit.

You will see both 440 and 440C in the naming around this size, and catalogues tend to use the two terms loosely. The precision steel balls supplied here are produced from 440C, the higher-carbon variant of the 440 family, which is what makes the HRC 58–62 hardness possible.

Grade G10 & Surface Finish

• What G10 controls — the grade sets how far diameter may vary across a batch and how closely each ball holds a true spherical form. G10 is the tight end of the G10–G1000 range we produce, and it is what you specify when the ball is one half of a precision fit.
• Why it matters at this size — a deviation that would be negligible on a 10 mm bearing steel ball is a large share of a 1.5 mm diameter, so grade is the first thing to settle, before price.
• Ground, not polished for show — the surface is ground to give a consistent, low-roughness contact face. It is a working finish, not a mirror finish.
• Sorted for batch consistency — the precision steel balls are graded and sorted, so a 10,000-piece lot behaves as one population rather than a mixture of sizes.
• How to verify on arrival — check a random sample from across the lot with a micrometer rather than only the first few pieces, and ask for a hardness check where the part carries load.
• Where a looser grade is enough — for weights, mixing media or purely visual parts, G100–G1000 does the job at a lower cost; describe the duty and we will quote the grade that fits.
• Cleanliness as supplied — balls leave packing clean and dry, without an oil or water film, so they can go into a clean assembly area without a degreasing step.

Stainless Grades & Applications

Where This Ball Is Used

• Miniature and specialty bearings — as a ball bearing ball in small bearing units and instrument pivots, where a 1.5 mm rolling element has to hold its roundness across millions of cycles.
• Valve and pump trim — check, seat and pilot duties in small valves and pumps. A large share of our output goes into this sector, including accounts that supply a stainless steel ball valve manufacturer with small trim components.
• Aerosol and sprayer pumps — aerosol pumps, garden and household sprayers and pre-compressed spice pumps, where the ball seats against a spring and has to seal on every stroke.
• Seam valves and medical application valves — small sealing balls for low-flow duties in medical and instrument valve assemblies.
• Agricultural backpack sprayers — anti-drip and check-ball positions on sprayer lines that see water, fertiliser solutions and outdoor conditions.
• Circulating ball systems — small-diameter circuits where a consistent stainless ball keeps flow and actuation predictable.
• Repair and hardware counters — a small steel ball kept on the shelf for replacements in pumps, sprayers and small mechanical assemblies.
• Industries served — food, chemical, naval and aerospace supply chains, alongside the general repair and hardware trades.

Product Video

The clip alongside the images runs about 44 seconds and is the closest you will get to holding the part before a lot lands. It shows the finished balls at close range: a single ball against the batch, the ground surface, and the uniformity you can expect across a full lot.

Watch for three things. Consistency comes first — the balls should read as one size across the frame, with no strays. Surface comes second: a finished stainless steel ball should look clean and evenly worked, with no oil or water film and no grinding marks left across the face. Appearance across the batch comes third, because an uneven finish usually supports a sorting or polishing problem that will show up again in your assembly.

If the clip raises a question — a grade, a material, a different finish — raise it with us before the order is placed, not after the lot arrives.

Assembly & Handling Notes

• Keep lots together — never tip a partly used 10,000-piece lot into another; a grade claim only holds for the lot it was tested with.
• Feeding on automatic lines — parts this small bridge easily in feed bowls and tracks, so match the tooling to the diameter and keep the feed steady rather than pulsing it.
• Wash and dry fully — the balls arrive clean and dry; if your process adds a wash, dry them completely so water spots do not mark the ground face.
• Mating surfaces — pair each stainless steel bearing ball with a seat or race of comparable hardness; a soft seat under a hard ball wears first, so check the counterface before you commit to the design.
• Sort, do not mix — keep G10 precision steel balls in their own labelled bin away from coarser stock, because a handful of the wrong grade is very hard to find once it is loose.
• Inspection sample — pull your sample from the middle of the lot rather than the top layer, and log the lot number so any future query can be traced back to the batch.

Ordering, Packing & Delivery

• Sales unit — multiples of 10,000 pieces.
• Batch pack — one 10,000-piece batch packs into roughly 15 x 10 x 5 cm and weighs about 0.170 kg, which keeps freight low relative to the value of the lot.
• Standard export packing — 20 kg per carton in woven bags, with carton on pallet or drum on pallet for larger volumes.
• Commercial packing — plastic bag + colour box + carton + pallet, when the lot is intended for commercial or catalogue distribution.
• Industrial packing — plastic + iron drum + pallet, or plastic + woven bag + wooden box, for bulk shipments.
• Bulk or soft boxes — goods are normally packed in bulk or in soft boxes sized for shipping containers, and we can pack to your own requirement instead.
• Shipping — sea freight, air freight or express, depending on volume and how quickly you need the lot.
• Ports of shipment — Qingdao, Tianjin, Shanghai and Ningbo.
• Payment terms — T/T with 30% as deposit and 70% before delivery; we send photos of the product and the packing before the balance is due.
• Delivery terms — EXW, FOB, CFR or CIF.
• Lead time — typically 10 to 15 days after the prepayment is received for standard lots; production against a deposit is usually quoted at around 20 business days. The figure is confirmed against your quantity and stock when the order is placed.
• Production to your sample — yes, we can produce according to your samples or technical drawings.
• Samples — where the size is in stock, ask your sales contact about sample availability for this product.
• Long-term supply — consistent quality, attentive after-sales service and competitive pricing are how we keep accounts running year after year.

Magnetic Response & Stray Fields

• What a magnet does: 440C is a martensitic stainless steel, so a magnet pulls these balls in directly. That is a property of the material, not a defect, and it stays the same for the whole lot.
• How it differs from the austenitic grades: 304, 302 and 303 are only slightly magnetic and annealing can render them non-magnetic, while 316 is non-magnetic. If a position must stay inert in a magnetic field, the grade decision comes before the size decision.
• Feeders and escapements: a 1.5 mm ball weighs very little, so even a weak stray field from a solenoid, a magnetic sensor or magnetised tooling is enough to hold it. Balls lift out of a track, stack at the gate of a feed bowl and arrive at the nest two at a time. Run a sample through your own tooling before the bulk lot ships.
• Separators and metal traps: a magnetic separator or tramp-metal magnet will take these balls out of the flow, which is useful for catching strays but wrong for anything that counts or meters product. Place magnets where you want removal, not upstream of a checkweigher or a vision station.
• Magnetically sensitive equipment: reed switches, Hall-effect sensors, magnetic levelling stages and beam or ion columns can all shift when a ferrous ball sits nearby. Where field sensitivity is the real design constraint, specify 316 stainless steel balls for that position and keep the 440C part for the loaded, moisture-exposed seat.
• Handling and retrieval: a magnet is the quickest way to recover a dropped small steel ball from a bench or a tray, but keep magnetic tools away from the bin that feeds a sensitive assembly, and do not store the lot beside magnetised fixtures.
• Residual magnetism: parts can pick up a slight field from magnet-assisted handling. If your process rejects magnetised components, say so when you enquire, because any treatment to remove it is a separate step and would be confirmed on the quotation.
• How to settle it: test a sample with a gauss meter at the actual working gap, then run it through the feeder, the separator and the inspection station in production configuration. Tell us the field strength and the distance involved and we will say whether 440C is the right call or whether this position should move to an austenitic grade.

Scale & Supply Capability

Yuncheng Kangda Steelball Co., Ltd., the factory behind the Condar brand, has been producing precision balls in Shandong, China since 2014 with a team of 80. Two factories handle production, while a 2,000 m² warehouse inside the Liaocheng logistics park keeps common sizes in stock so ordered sizes can leave quickly. More than a hundred sets of production and inspection equipment work to GB/T308.1-2013, backed by ISO documentation and RoHS/REACH material statements. Customised or made-to-order items can be quoted case by case.

FAQ