10mm-20mm Newton pendulum ball polished mirror finish steel ball

Product Overview

A Newton's cradle only looks convincing when every ball is the same size, the same mass and the same quality of reflection. This is a solid steel ball in the 10–20 mm band, ground to round and then polished through its final stages until the surface behaves like a mirror — one clean highlight instead of a scatter of fine lines. Nothing is plated onto it and nothing is coated over it, so there is no layer that can flake at the edge of a reflection or wear through where two balls touch.

Weight sets the frame, not the load

A pendulum ball hangs still for most of its life and takes load only at the instant of impact, so the figure that matters is mass rather than a load rating. Steel ball weight climbs steeply with diameter — a 20 mm ball carries roughly eight times the mass of a 10 mm one — so the diameter you choose fixes the frame size, the string spacing and the swing the finished piece will produce. Ask us for the weight figure for the exact diameter you plan to use before the frame is drawn, and order the whole set together so it comes from one production lot.

Where our supply sits

We are one of the steel ball manufacturers based in Shandong, and this mirror-polished finish is supplied both as cradle components and as loose stock for gift sets, trophies, teaching models and shop displays. The same polish is available from 6.0 mm up to 38.1 mm, so a designer can carry one finish across a small desk piece and a larger floor-standing model without changing supplier halfway.

Grade and tolerance in a display part

Nothing in a pendulum runs at speed under load, so a cradle does not need bearing tolerances. It does need every ball in a set to be the same, which is why the balls are supplied to a declared grade between G10 and G1000 and picked per lot rather than scooped from mixed stock. A matched set matters more here than the tightest single tolerance we could produce.

Specifications

Video Description

• What the clip covers — a 30-second clip of the pendulum balls themselves, so the surface is seen in movement rather than as a still frame.
• What to watch for — as the ball turns, a true mirror keeps a single continuous highlight and holds a reflected edge straight; a shallow polish breaks the highlight into bands and softens the edges.
• Scale in the hand — moving footage is more useful than a photograph when you are deciding between a 10 mm and a 20 mm ball for a desk piece, because the ball is seen at working size rather than at studio size.
• Where the clip stops being evidence — screen colour settings, compression and the light in the room all change how a reflection reads, so treat it as a guide to the character of the finish and confirm the polish against a physical piece of the diameter you intend to order.
• Passing it on — the clip is short enough to send to a frame maker or a client who has to approve the look before the piece goes into production.

Mirror Finish & Handling Care

What the polish actually is

Grinding brings a ball to size and roundness but leaves fine directional lines across the surface. Polishing removes them in stages until the reflection has no halo left in it. A finished stainless steel ball should show one undistorted highlight under a desk lamp and hold the edge of a window as a straight line rather than a soft blur. Judge a set rather than a single ball: several balls that each reflect slightly differently will look mismatched even when every diameter measures correctly.

Where the finish is lost before it is fitted

Skin oil is the commonest cause of a dull patch. A print left on a polished metal ball for a few weeks can etch faintly into the surface, and that mark does not simply wipe away afterwards, so wear clean cotton or nitrile gloves whenever you handle balls that will be seen. Loose storage is the second cause: two balls knocking together in a bag dull each other at the contact point, and the contact point is exactly where the eye lands on a finished cradle.

Cleaning and environment

Warm water with a drop of mild detergent, a soft cloth, then a dry cloth straight away is all this finish needs. Scouring pads, abrasive cream, acid-based descalers and chlorine cleaners dull it permanently rather than temporarily. In a damp workshop or a coastal showroom, condensation spots appear on any polished steel surface left uncovered, so keep spare stock sealed with a desiccant sachet until it is fitted.

What to check on receipt

Open the cartons in a clean, dry area, leave the balls in their pockets until assembly, and inspect under a point light rather than ambient daylight — a dull patch that is invisible in soft light is obvious under a spotlight. Flag any ball that shows a scratch, a handling print or a reflection that breaks into bands before the set is built up.

Display, Gift & Teaching Uses

• Desk and shelf Newton's cradle — five or seven matched balls hung from a frame, where the swinging ball and the resting balls have to be indistinguishable; the frame has to carry the steel ball weight of the diameter chosen, so the whole set should come from one lot.
• Executive and award pieces — a polished ball set into a wooden or acrylic base as a trophy or retirement gift, an object that stands or falls on its reflection, where one scratched ball spoils the whole piece.
• Physics teaching models — classroom cradles take far more handling than a desk piece, which is where the unplated surface earns its place, since there is no coating to wear through after a term of demonstrations.
• Gift and presentation packaging — small steel ball kits boxed with a folded frame for museum shops, bookshops and science-toy ranges, packed so the balls cannot knock together in transit.
• Visual merchandising and photography — a single ball used as a paperweight, a display prop or a photographic reference, where one clean sphere carries a whole composition.
• Replacement balls for a cradle already in service — where the originals have been lost or have gone dull, measure the old ball's diameter and note how it reflects before reordering, so the new set blends with what the customer already owns.

Packaging & Delivery

Monthly Supply Capacity

The polished line runs at 18,800,000 pieces a month, which describes a process that runs continuously rather than in occasional campaigns.

Why that matters on a repeat order

A gift range that sells through a season needs its second and third order to look like the first. A line that runs every month can hold a diameter and a polishing setting across runs; a line that starts and stops re-sets between batches, and re-setting is where a reflection starts to drift. The thing a repeat buyer is really paying for is sameness — the same metal ball, the same reflection at the same diameter and the same weight, whether it is the first shipment or the ninth.

Mixing diameters in one shipment

Because the same polishing setup covers 6.0 mm through 38.1 mm, one order can carry several diameters — a 10 mm desk model, a 16 mm gift piece and a 20 mm display set — and they will arrive together and reflect the same way. That matters when the frames are being assembled in the same workshop and the finished pieces will stand side by side on the same shelf.

Planning a scheduled program

For a repeating program, give us the diameters, the grade and the quantity per size and we will confirm what can be held between runs. Normal volumes sit comfortably inside the monthly figure, and larger campaigns are scheduled across production runs so the finish stays consistent from the first shipment to the last. Buyers sometimes spread an order over several steel ball manufacturers because they are unsure a size will stay the same from run to run; continuous output is what lets a repeat order be matched to the original specification instead of being re-sampled.

Inspection & Testing

1. Rockwell hardness check — every batch is tested on a Rockwell hardness tester and recorded as an HRC value. For reference, bearing steel balls normally sit at HRC60–66, stainless balls around HRC26, carbon steel balls at HRC55–65, and soft carbon steel balls near HRC30.
2. Roundness check — G5 and G10 balls are measured for ellipticity on a roundness meter, which traces the profile and lets the equipment plot the deviation. A solid steel ball can measure the right diameter and still be out of round; this is the check that catches it.
3. Diameter measurement — tolerance is verified with a micrometer or a spiral micrometer, and larger balls with vernier callipers. This is the step that decides whether a batch ships against its stated grade.
4. Surface inspection — a visual pass under a point light for the polish itself, looking for dull patches, residual grinding lines and handling marks before the balls go into their pockets.

440C Stainless Steel Chemistry

Stainless Steel Grades & Range

• 304 / SUS304 — the general-purpose austenitic grade: good corrosion resistance, good heat resistance, useful strength at low temperature, non-magnetic and it does not harden under heat treatment. It stands behind most household goods, cabinets, indoor piping, water heaters, boilers, bathtubs, automotive parts, medical devices, building materials, chemical equipment, food-industry parts, agricultural equipment and ship fittings.
• 316 and 316L — the grades chosen where chloride, sulfuric acid or process water would attack 304; 316L runs a lower carbon level for welded assemblies.
• 420, 440 and 440C — the hardenable martensitic grades, used where the ball has to resist wear as well as rust. 440C appears in stainless steel ball bearings, pump and valve parts, motor components, pulleys, plastic bearings and instrument work, and it is the grade set out in the chemistry table above.
• 201, 202, 302, 303 and 204 — the remaining austenitic grades held for cost-sensitive work and for parts that need free machining.
• Coverage — every grade is available as a small steel ball from 0.3 mm up to 50.8 mm, in grades G10 to G1000; the mirror polish on this product is normally supplied between 6.0 mm and 38.1 mm.
• The rest of the plant — the same works also produces bearing steel balls, miniature balls from 0.3 mm, extra-large bearing balls, plated balls, drilled and machined balls, ceramic balls in silicon nitride, silicon carbide and zirconia, and H62/H65 brass balls.

Drilled & Threaded Mounting

• The grade decides whether it can be drilled — the 304 and 316 stainless steel ball sizes we prepare for thread drilling run at HRC26–30, soft enough to take a cut and a thread; the wear-resistant 440C balls sit at HRC50–55, and 440C precision balls at HRC58–62, which is a different job for tooling. Choose the grade with the hole in mind rather than after the frame has been drawn.
• Threaded balls in the 10–15.8 mm band — 304 or 316 balls in this size range, grades G10 to G1000, are what we normally prepare for thread drilling, and the mirror polish can be carried on the same diameter. A tapped ball turns the sphere into a fixing point: it can be bolted to a plate, a rod end or a frame upright instead of resting in a cup.
• What the cut does to the reflection — drilling opens the polished skin and leaves an edge at the entry, so a machined ball will not read as one clean sphere the way an untouched solid steel ball does. If the hole will be seen on the finished piece, tell us at the enquiry stage; finishing around a machined opening is a different piece of work from polishing a plain sphere, and we will say what is realistic for that diameter rather than promise a mirror over a cut edge.
• Fixed point or free ball — a plain ball has to be seated: a socket, a cup, a shallow drilled plate, a length of cord. A drilled ball takes the seat out of the design and makes the ball a permanent fixture, at the cost of the finish and a little mass. Where the ball only has to look right and swing, design around the plain sphere and keep the machined version for the anchor points.
• A drilled ball loses mass — removing material changes steel ball weight, and in a cradle every hanging ball has to match the others. Keep machined balls out of the swinging line, or place them symmetrically so the motion stays even; one drilled ball among plain ones will not swing true.
• What to send with the enquiry — a sketch is enough: nominal diameter, hole diameter and thread (M3, M4, M5), through or blind, depth, position on axis or offset, the positional tolerance you need, quantity per size, and whether the hole will be visible. Depth is limited by the ball diameter and by the wall left around the hole, so a 10 mm ball cannot take the same thread depth as a 20 mm one.
• Ordering machined and plain together — machined balls are quoted case by case, so list them alongside the plain balls in one enquiry and we will keep diameters matched and finish consistent across the set. Threads and cut edges are packed separately from polished stock so the parts cannot mark each other in transit. Drilling and machining also covers carbon steel balls where the part does not need stainless.

Important Attributes

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