Tungsten Carbide Reaming Pin

Product Overview

A reaming pin is the small, hard part that decides whether a reamed hole finishes on size, and it takes the wear that goes with the job. This one is machined from solid tungsten carbide with a ground point at the tip, a stepped cylindrical shank behind it, and a flat milled notch cut across the shank. The point centres the pin in the bore, the step seats it at a repeatable depth, and the flat gives the clamp something to bite on so the pin cannot turn. Ground carbide has its own look — a dull silver-grey with a sheen on the working surfaces rather than a painted or coated finish.

Most of the tungsten carbide parts we produce go into air-conditioning and electrical appliance manufacturing, and this pin is typical of that world: compact, run in a fixture or a hand tool, and expected to hold a diameter where a steel pin would polish away and start cutting oversize. Plenty of them are replacement orders rather than new builds. A maintenance technician notices a hole drifting out of tolerance, strips the holder down, and finds the pin has gone under size or chipped at the point.

In use, the operator drops the point into the bore, seats the shank step against the holder face so the depth repeats from part to part, and tightens the clamp onto the flat. Because the notch stops the pin rotating, the tip angle stays where it was set and the cutting edges meet the bore the same way on every cycle — which is the difference between a bore that repeats and one that has to be checked twice.

Nothing here is picked from a size chart. Every pin runs through our custom CNC machining service against a customer drawing, so working diameter, overall length, tip angle, step position and notch geometry are whatever your print calls out.

Key Features

• Carbide that keeps its diameter — tungsten carbide resists abrasive wear far better than tool steel, so the working diameter stays where it was ground instead of drifting oversize partway through a run.
• Pointed lead-in tip — the ground point centres the pin in the bore before the working section touches, which keeps the entry concentric and stops the corner chipping on an off-centre start.
• Stepped shank for repeatable depth — the step registers against the holder face, so a replacement pin sits at the same height as the one it replaced.
• Flat milled notch — a set screw or clamp bites on the flat instead of the round shank, holding the pin against rotation and against being pulled out under load.
• Ground working surfaces — the diameter and tip are finished to the drawing callout rather than left as turned, which is what makes the fit repeat from one order to the next.
• No catalogue size to compromise on — the drawing sets working diameter, overall length, tip angle and notch position, so the pin matches the holder you already have.

Geometry & Working Surfaces

Carbide grade. Tungsten carbide covers a wide family of grades, and the right one depends on how the pin fails. A grade built for abrasive wear holds a diameter in a filled or glass-loaded material; a tougher grade survives the shock of an interrupted cut or a holder that is not perfectly aligned. We settle this with you at the drawing stage rather than shipping whatever is nearest the door.

Working diameter and tip. The point is ground to the angle on your print. A shorter, steeper point is stiffer and suits a shallow entry chamfer; a longer point guides better in a deep bore but leaves less carbide behind the tip. The working diameter behind it is ground into the tolerance band you specify, with the transition blended so the pin does not dig at the start of the cut.

Shank and step. The shank is turned and ground to fit your holder, and the step face has to sit square to the axis — a step that is even slightly off square seats the pin at an angle and reams a tapered hole. Give us the holder bore and the step depth, and the shank follows from them.

Notch. Width, depth and position come from the clamp or set screw you already use. A notch that is too shallow lets the pin creep under load; one that is too deep removes material exactly where the shank carries its load.

Finishing. Working surfaces are ground after the profile is cut, and edges are lightly broken so the pin does not chip when it is handled or dropped into a holder. This is the part of the job where custom precision machining earns its keep: the difference between a pin that fits and one that nearly fits usually comes down to a handful of details on the print.

Specifications

Applications

• Reamed hole sizing on appliance sheet parts — hinge brackets, panel mounts and frame holes where the pin has to bring a drilled hole to final size and hold its position.
• Bores in electrical components — terminal carriers, contact holders and connector bodies, where a burr or an oversize bore shows up later as a fit problem.
• Bushing and sleeve finishing — bringing a pressed-in bushing back to size after installation has distorted the bore.
• Press tool and fixture maintenance — reconditioning worn guide and location bores on tooling already in service, without stripping the whole tool.
• Salvage and rework — a hole drilled under size or pulled slightly oval that can be brought back to nominal instead of scrapping the part.

Drawing & Quotation Steps

1. Send what you have — a dimensioned 2D drawing, a 3D model, or the worn pin itself if that is all that exists.
2. Mark the working dimensions — working diameter, overall length, tip angle, shank diameter, step depth, and the width and position of the flat.
3. State the fit you need — the finished bore size and the tolerance band you work to, so the pin is ground to the middle of it rather than to nominal.
4. Describe the job — the material being reamed, hole depth, whether the cut is continuous or interrupted, and how the pin is held.
5. Say what stage you are at — one trial pin, a pilot run, or production volume. If you are still at the rapid prototyping stage, a 3D model is enough to start.
6. We review and quote — as part of our custom CNC machining service we come back with notes on anything that will be expensive to change later, plus quantity, price and delivery for your approval.

Ordering & Delivery

• Order quantity — No hard minimum order requirement; confirmed per drawing and order.
• What the quotation covers — unit price, any setup or tooling charge, and delivery, all confirmed against your drawing and quantity.
• Lead time — confirmed at quotation; it moves with the number of ground features and the quantity on the order.
• Payment terms — agreed with your sales contact when the order is placed.
• Packing — carbide edges chip, so pins travel packed so they cannot knock against each other; tell us if you need individual labelling for a stores issue.
• Shipping — freight method, destination and documents are agreed per order, and we ship regularly to long-standing customers in Europe, the US and Southeast Asia.
• Repeat orders — every custom precision machining job is kept against its drawing reference, so a reorder months later runs to the same dimensions.

Quality Inspection

Nothing leaves the floor without being measured. Key dimensions — working diameter, overall length, step depth, notch position and tip angle — are checked against the drawing, along with a visual pass on the point and edges for chips or grinding marks that would show up as a poor finish in the bore. Full QC inspection runs through production as well as before shipment, which is what keeps a second batch close to the first.

If your quality team needs a first article, or a single pin to try in the holder before releasing volume, say so at quotation. Proving the geometry on a trial part settles the shape before volume commits to it, and a first article is the simplest way to sign off a new drawing.

Records are kept against the drawing reference, so a question about a delivery a year later has something concrete to measure against rather than a memory of a conversation. The next run of this custom precision machining job starts from the same file, not from a fresh reading of a sketch.

Related Carbide Tooling

• Valve seat guide mandrel — a guided mandrel for valve seat machining and assembly, where the tool has to hold concentricity through the cut.
• Tungsten carbide square punch — a square-profile punch for cutting and forming, working an edge rather than sizing a bore.
• Tungsten carbide screw — a threaded carbide fastener for joints that wear or run hot, where a steel screw would not hold.
• Tungsten carbide mandrel — the general wear-critical guiding mandrel, alongside the sealing mandrel used for leak-tight assembly work.
• Other reaming pin sizes — Tungsten Carbide Reaming Pins with a different diameter or configuration are listed separately; if you are unsure which one matches your print, send the drawing and we will confirm.
• One material family, one inspection route — all of these are tungsten carbide parts ground to customer drawings, so a mixed order can be checked and packed together.

Pin Family & Replacement

We list two reaming pin configurations, and they are separate sizes and builds rather than the same part twice. If you are replacing a worn pin, the reliable starting point is the finished hole and the holder, not the old pin: measure the bore the pin has to produce, the holder bore, the step depth and the flat width, and note the tip angle if the point is still intact. A pin that has worn under size will measure smaller than the hole it was made for, so working from it alone tends to order a part that is already too small.

Where a fixture is still being developed, we can work from a rapid prototyping model first and lock the drawing once the geometry has been proven in the holder — cheaper than committing to production on a shape nobody has run yet.

A reaming pin is not interchangeable with the rest of the range. It is not a punch and should never be struck; it cannot stand in for a mandrel in a guiding application; and the shank step is specific to the holder it was drawn for. What can change is the carbide grade, the tip angle, the diameter and the notch, and any of those can be revised on a new drawing without touching the holder.

When the point chips or the working diameter drops below the band, the pin is finished as a repair item — carbide does not take kindly to being built back up. That is why most customers keep one spare in the tool crib rather than waiting for a line to stop.

Technical Support & Model Matching

Send your drawing and our engineering team reviews it with you before production starts: confirming dimensions, tolerances and fit, matching material grade and wear surface to your working conditions, and flagging details that are costly to correct later. Ten years in this industry means most problems have already crossed our bench, so we also support troubleshooting on parts in service, fitting and setup guidance, and supply for discontinued items. Buyers in Europe and Southeast Asia work with us on that basis; every order is machined to your drawing, never pulled from a catalogue.

FAQ