Cut, ground and finished in Shandong, this 3.175 mm (1/8 inch) ball is made from 440C stainless steel to grade G10 and hardened to HRC 58-62. It is a solid stainless steel ball rather than a plated one, so the surface that runs against a seat or a race is the same material all the way through.
This size sits in the middle of a great deal of pump and valve work. Aerosol and perfume pumps, garden and household sprayers, pre-compressed spice pumps, seam valves, medical application valves and agricultural backpack sprayers all use a ball in this range to seat, seal or meter. The same ball goes into specialty bearings, circulating balls and general product parts, where a bearing steel ball this small has to cope with movement and moisture at the same time.
Buyers arrive at this size from two directions. Some are specifying a new pump or valve and want a defined grade with a hardness figure behind it. Others are repair shops and hardware suppliers replacing a worn or lost ball in equipment that is already in service. Both receive the same product: a ground 440C ball, sorted to G10 and packed for export.
Much of what we ship ends up in pump and valve assemblies, and a stainless steel ball valve manufacturer buying this size is usually matching it to a seat tolerance rather than shopping on price. If that describes your order, the specifications and the grade notes below are where the detail sits.
| Property | Value |
|---|---|
| Product name | Stainless steel balls, 420 and 440 material |
| Model and size | 3.175 mm (1/8 inch) |
| Material | 440C stainless steel |
| Brand | Condar |
| Grade | G10 |
| Hardness | HRC 58-62 |
| Surface | Grinding |
| Function | Corrosion resistant and wear resistant |
| Application | Bearing parts and product parts |
| Applicable industries | Repair shop, hardware accessories |
| Certification | ISO, RoHS |
| Country of origin | Shandong, China |
Why 440C. 440C is the hardenable stainless grade in our range. It responds to heat treatment, which is how this ball reaches HRC 58-62 while still behaving like stainless steel in a wet working environment. In a pump or valve that combination matters more than either figure on its own: the ball has to close against its seat thousands of times without taking a dent, and it has to do that in process fluid, condensate or wash-down water without rusting between shifts.
What G10 controls. The grade is about consistency as much as accuracy. A G10 ball holds a tight band on diameter, roundness and surface finish, which is what lets it feed through automated assembly tooling and seal on the first pass rather than the third. Parts built around a stainless steel ball this small usually fail on batch variation rather than on the material, so the grade is where the effort goes.
Hardness as a range. HRC 58-62 is quoted as a window because hardness is measured on samples from the batch, not on every individual ball. What you buy is a batch that sits inside that window, so a check during your incoming inspection should land in the same place as ours.
Surface and contact. The ball is finished by grinding, which gives a controlled, even surface and a defined contact patch against a seat or a race. Keep the balls in their packing until assembly; a ground 440C surface will mark if it is rolled loose across a bench.
Where it stops. This is a bearing steel ball in behaviour and a stainless one in composition. Where steel balls for bearings carry heavy cyclic load, chromium bearing steel such as 100Cr6 is the usual choice, and where the duty is strongly acidic or marine, the 316 grades are the better match. 440C sits between the two, which is where most pump, valve and aerosol mechanisms actually live.
| Grade | Character | Typical applications |
| 304 / 302 / 303 | Austenitic material, corrosion resistant, slightly magnetic; however, annealing can render it non-magnetic | Valves and related applications, food, aerosols, household sprays, perfumes and medical devices |
| 316 | Non-magnetic, good corrosion resistance even in marine atmospheres and sulfuric acid | Sulfuric, phosphoric and acetic acid service; chemical, papermaking and textile industries |
| 316L | Same properties as 316 with lower carbon and improved corrosion resistance | Jewelry and implant applications |
| 52100 / 100Cr6 chromium bearing steel | Through-hardened, HRC 60-66, not stainless | High-load bearing races and heavy cyclic duty |
| 440C, this ball | Hardenable stainless, HRC 58-62, ground finish, corrosion and wear resistant | Pumps, valves, aerosol mechanisms, specialty bearings and product parts |
The product video shows this ball at close range, and it is worth watching the surface first. A ground 440C ball should read as an even, unbroken finish under the light, with no flats, laps, soft patches or plating lines, because there is no plating on it to hide behind. Then look at the batch behind the close-up: when the diameter band is holding, the balls sit at a consistent size against one another, which is what you want to see before a run goes into automated feeding.
A short clip also answers things a specification cannot. How the balls are weighed and packed, how a carton is lined, what a pallet looks like before it is wrapped. If you need to see something specific before ordering, such as one of these balls offered up to your own seat, the packing configuration you intend to use, or a batch shot beside your drawing, ask and we will send the footage or photographs you need.
Standard supply. Against this size we supply a solid, ground 440C ball with no hole, no thread and no coating. Nothing is added to the surface, so what your seat runs against is the same 440C through the full section.
Drilling and threading. At this size there is little material to give: a cross-hole or a tapped bore takes a real share of the sphere, so the drawing has to show where the feature sits, its diameter or thread, and how much wall is left at the working surface. We quote these from the drawing rather than from a description, and the honest answer is sometimes that the size is too small for the feature and the next size up is the practical route. Our stainless steel balls prepared for thread drilling sit mainly in the 10–15.8 mm range in 304 or 316, where there is enough wall to work with.
Plating. Plating is its own material line: our plated balls are a carbon steel core with gold, silver, nickel, zinc or coloured finish, G1000 and around HRC 27. A coating on a hardened 440C precision ball is a different proposition, so if the finish is the point of the part, tell us what the coating has to do — appearance, colour match, solderability — and we will say whether the plated line or a machined part is the better fit.
What a quote needs. Quantity, a drawing with tolerances, the thread or hole specification, the surface requirement, and whether the operation runs before or after heat treatment. That last point changes the hardness the ball ends up with, and it has to be settled on the drawing rather than at the machine. Where the feature is small, a sample you have already modified yourself is often easier to quote from than a dimension on paper.
Compliance documents. The material, grade and hardness range are recorded on the packing documents, so an incoming inspection has a figure to check against, and REACH statements can be confirmed for your order on request.
Food and medical work. Medical application valves and pump components are among the places these balls are used, but being used in a medical assembly is not the same as holding a medical approval. We do not supply food-contact or medical-device approval documents with this ball. If your market requires a food-contact declaration or a device approval, raise it at enquiry with the regulation or standard your line works to, and we will confirm exactly what can travel in the file before you commit — better that than a container stopped at your border.
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.
Yes, 3.175 mm is exactly 1/8 inch (0.125 in), and that is the size this ball is made to. It will not substitute for a 3 mm ball: it is 0.175 mm larger and will not drop into a nominal 3 mm seat. If your drawing is imperial, order this size; if it is metric, send the bore and seat dimensions and we will confirm which stainless steel ball suits it. As a rule of thumb, a small steel ball should drop in and lift out freely, so if it needs force the size is wrong.
The grade describes how tightly the finished ball holds its nominal diameter, how round it is, and how consistent the surface is. G10 is a tight band, which is why these balls feed through automated assembly and seal on the first pass. For stainless steel bearing balls this small the grade is the specification that decides whether a batch runs, not an optional extra. Every batch is checked before packing, and if your drawing asks for recorded values, tell us what you need and we will confirm which inspection data can travel with the shipment.
Standard supply is a solid, ground 440C ball. Drilling, threading and plating are secondary operations we quote case by case, so send the drawing with the position and thread details and we will confirm feasibility and timing before you commit. At 3.175 mm the drawing decides whether a modification is practical, which is why we quote from the drawing rather than from a description.
In pump and valve service 440C is the practical middle ground: hard enough to resist wear at the seat, and stainless enough to cope with process fluid, condensate and wash-down water. It is not the grade for aggressive chemical duty — for sulfuric, phosphoric or acetic acid service, or a marine atmosphere, the 316 grades in our range are the better match. If you are unsure which side of that line your application sits on, tell us the fluid it sees and we will say which material we would put in it.
These balls are used in medical application valves and pump components. Food-contact and medical-device approvals are a separate question, settled by the documents your application requires rather than by the material name alone. Tell us which standard your line works to and we will confirm what we can provide before you place the order.
This size is produced in 440C, hardened to HRC 58-62 and finished by grinding, and that is the material and hardness shown on the packing documents. 420 and 440 describe the martensitic stainless family our stainless line covers, so the name lists both even though a given order is made in one grade. If your drawing specifies 420, say so at enquiry — it behaves differently in hardness and we will confirm what we can supply against your requirement.
