JTWP Oilless Wear Plate
We provide custom manufacturing of finished bronze parts and self-lubricating bronze, precisely based on our clients’ drawings.
JTWP Oilless Wear Plate: Dimensions and Load Ratings
JTWP is the series designation used for graphite-plugged cast bronze wear plates: a flat load-bearing plate with solid lubricant embedded in the working face, machined to the outline the machine needs. They are specified where a surface has to slide under load with no oil or grease supply — inside molds, under jacking mechanisms, on bridge bearings and in equipment that cannot be shut down to re-lubricate. This page sets out the construction, the design limits and how to fit one, plus the duties where a different component is the better choice.
What the designation covers
The JTWP series sits alongside the other oilless plate and washer series. JESW oilless wear plates and JSOL oilless wear plates cover their own size bands and base alloys, and JTW oilless thrust washers handle axial loads in the same construction. JTWP is the plate form: rectangular or shaped, bolted or bonded into a housing, carrying load normal to its face.
What all of them share is the lubrication method. The body is a cast copper alloy; the working face carries a pattern of holes filled with solid graphite plugs. As the mating surface slides, a microscopic layer of graphite transfers onto it and forms the film that carries the contact, renewing itself on each stroke — which is why the plate needs no external lubricant.
Typical design data
These are the figures used at the quotation stage for copper-based inlaid plates. They should be treated as typical for the material class, not as a rating for a specific part number.
| Parameter | Typical value | Note |
|---|---|---|
| Base material | High-strength brass such as CuZn25Al6Fe3Mn3, or aluminum bronze where temperature or corrosion requires it | Alloy selected after the duty is known; see cast bronze oilless materials |
| Base hardness | HB 210–245 | Measured on the cast body |
| Maximum dynamic load | 100 N/mm² | Steel-based plates reach about 250 N/mm² |
| Maximum operating temperature | 300 °C (572 °F) | Above this the rating no longer applies |
| Coefficient of friction (μ) | 0.04–0.16 | Varies with load, finish and medium |
| Duty profile | High load, low speed; oscillating or intermittent travel | Not for continuous high-speed sliding |
| Counter face | Hardened steel, Ra 0.8 µm (32 µin) or better | A soft face is scored rather than polished |
| Typical plate thickness | 6–30 mm (0.24–1.18 in) | Length and width to drawing |
Values are typical for copper-based inlaid material and depend on plate thickness, seating flatness and counter-face condition. The certificate supplied with each order governs.
Plate forms and where each is used
| Form | Geometry | Typical application |
|---|---|---|
| Plain plate with countersunk holes | Rectangular, holes sunk below the working face | General sliding support faces, machine tool wear plates |
| Plate with oil grooves | Grooves machined into the face, with or without plugs | Duties with an intermittent grease supply where plugs cover the dry periods |
| Segment or wedge plate | Tapered or shaped outline | Segment wedges and adjustable jacking mechanisms |
| Stepped or shouldered plate | Plate with a locating shoulder or step | Housings that need positive location as well as a bearing face |
| Matched sliding pair | Two plates, one fixed and one sliding | Structural bearings and large travel assemblies |
Where these plates are specified
| Industry | Condition | Why a plugged bronze plate is used |
|---|---|---|
| Manufacturing and special machines | Lubrication is difficult or undesirable at the wearing surface | No oil means no product contamination and no grease lines |
| Mold and die work | Intermittent sliding under high closing load | Plates run dry at the parting face and inside multi-cavity molds |
| Food processing | Hygiene standards rule out oil and grease near the product | Dry running removes the contamination risk |
| Textile, paper and packaging | Dust and debris interfere with lubrication | Solid lubricant is unaffected by lint and dust |
| Heavy plant and structural work | Thermal or settlement movement under load, no maintenance access | Same construction as bronze plate bridge bearings and refinery pipe shoe plates |
| Mining and quarrying | High load, slow movement, abrasive dust | Debris does not destroy the film; see mining wear plates |
Selecting and fitting a JTWP plate
- Work out the contact pressure. Divide the load by the projected contact area and keep the result below 100 N/mm² for copper-based plates. Most undersized plates fail because the area was estimated from the machine footprint rather than the actual contact patch.
- Check PV, not just P. A low pressure at high sliding speed can generate more heat than a high pressure at low speed. These plates are designed for high load at low to moderate speed.
- Size the plug pattern to the stroke. Every point on the counter face must pass over a plug during a full stroke, otherwise dry zones appear. The layout method is given in plug size calculation for graphite-plugged bronze.
- Specify the counter face. Hardened steel at Ra 0.8 µm (32 µin) or better, flat and fully seated. Plate performance is limited by the condition of the surface it runs against.
- Fix below the working face. Countersunk screws must sit under the surface; where the housing allows, welding or bonding the plate is preferred because it removes the fastener problem entirely.
- Seat it fully. A plate bridging a gap in the housing will bend and crack. Machine the pocket flat and check contact before final tightening.
- Allow for thermal growth. Bronze expands more than steel — typically about 18 × 10⁻⁶/K against 12 × 10⁻⁶/K — so clearances set at 20 °C (68 °F) should be checked against the operating temperature. Recording as-built dimensions at 20 °C (68 °F) also lets the replacement plate match without a survey.
Limits: when not to specify a JTWP plate
- Contact pressure above 100 N/mm². Specify a steel-based inlaid plate or increase the area. An overloaded copper-based plate extrudes and closes the plug holes.
- Sustained temperature above 300 °C (572 °F). The base alloy loses strength and the graphite oxidises.
- Continuous high-speed sliding. Heat cannot dissipate and the transfer film is removed faster than it reforms. A rolling or recirculating guide handles that duty.
- Rotating shafts. A plate is a flat bearing surface. Shaft support needs a bushing, not a wear plate.
- Ammonia or acetylene atmospheres. Copper alloys are not compatible with either.
- Applications that need elastic deflection or misalignment. A flat plate does not accommodate angular movement; a spherical bearing or an elastomeric pad is required.
- Load cases where the counter face cannot be hardened. Against soft steel or aluminium, the plate will gall.
What to send for a quotation. Plate outline drawing with length, width and thickness in mm or inches, hole positions and countersink detail, load, stroke and cycle rate, operating temperature range, counter-face material and finish, and quantity. A sample of the existing plate is enough to reproduce one.
Frequently Asked Questions (FAQs)
High-Performance Oil-Free Wear Plates for Industrial Machinery
Email us your production files, or reach out to schedule a call with our expert team.
Email us your production files, or reach out to schedule a call with our expert team.
Email us your production files, or reach out to schedule a call with our expert team.
Email us your production files, or reach out to schedule a call with our expert team.
Email us your production files, or reach out to schedule a call with our expert team.
Email us your production files, or reach out to schedule a call with our expert team.
