Plastic Bevel Gears

Plastic bevel gears have a conical shape with straight or spiral-cut teeth and transmit motion between two axles that intersect, changing the rotation axis direction. They are the standard gear type for 90° direction changes in compact drives — power tools, automotive applications, food production machines, consumer electronics, chemical equipment, toys, and medical equipment. Korea Ever-Power's plastic bevel gears are available in Plastic, POM, and Nylon (and other materials as required), module M0.25 and up, with ratios 1:1, 2:1, 3:1, 4:1, 5:1, operating temperature −40°C to +80°C. Standard catalogue dimensions from M0.5 (GB05M016) through M1 and above, in both 1:1 and other ratios.

Korea Ever-Power's plastic bevel gears offer: lightweight and non-rusting construction; quiet operation (especially the spiral-cut variant which is smoother and less noisy than straight bevel); injection-moulding enabling low cost and large production volumes; ability to operate without lubrication by mating with metal gears; and a wide choice of standard sizes from the Korea Ever-Power catalogue. The degree of dimensional change with temperature, moisture absorption, and chemical exposure depends on material grade — Korea Ever-Power advises on the correct material for each application.

1:1 Ratio Set

Nylon Pinion

Custom All Ratios

ODM Custom

General Specification

M0.5 and M1 Standard Catalogue (1:1 Ratio, sample)

Full dimensional table (CD, hub dia, boss length, tooth width, length) available on request. 2:1–5:1 ratios also available in standard range.

Conical Pitch Surface

Bevel gear pitch surfaces are cones — the apex of both mating bevel gears' pitch cones coincides at the intersection point of the two shaft axes. The teeth are cut on the conical surface, decreasing in size from the large (heel) end to the small (toe) end. The tooth form varies along the face width to maintain the correct involute profile at the mean pitch diameter, where tooth load analysis is typically performed. This tapering tooth form distinguishes bevel gears from cylindrical gears and makes them the only standard gear type for intersecting-shaft power transmission.

Straight vs Spiral Bevel Teeth

Straight bevel gears have teeth cut radially on the cone surface — the teeth are parallel to the pitch cone generatrix. They engage abruptly across the full tooth width, producing an impulse at each tooth mesh (similar to spur gears). Spiral bevel gears have curved, oblique teeth — contact begins at one end and progresses gradually, like helical gears. The spiral bevel version is smoother and less noisy than straight bevel on all designs — at the cost of higher manufacturing complexity and the presence of an axial thrust force in both bevel shafts that must be reacted by thrust bearings. Korea Ever-Power's plastic bevel gears are available in both tooth forms.

Gear Ratio and Shaft Angle

Bevel gear ratio i = Z₂/Z₁ = tan(δ₁)/tan(δ₂) — where δ₁ and δ₂ are the pitch cone angles of the pinion and gear respectively. For 90° shaft angle bevel gears, the two pitch cone angles sum to 90° (δ₁ + δ₂ = 90°). For a 1:1 ratio, both gears have δ = 45° and are geometrically identical (miter gears). For higher ratios (2:1, 3:1), the pinion has a smaller cone angle and the gear has a larger cone angle. Korea Ever-Power's standard catalogue covers 1:1 through 5:1 at modules M0.5 and M1; custom ratios available.

Operating Without Lubrication

Plastic bevel gears can operate without lubrication — especially when the plastic bevel gear meshes with a metal gear (typically the harder material is metal, and the plastic gear acts as the softer, sacrificial wear element). The POM bevel gear's inherently low friction coefficient (μ ≈ 0.1 against steel) provides adequate lubrication through the POM surface's tribological properties without requiring added oil or grease. This dry-running capability is essential in food industry, medical, and clean-room applications where lubricant contamination is unacceptable.

Plastic Bevel Gear Cautions

Plastic bevel gears require design caution for three characteristics: (1) Low strength — plastic bevel gears have lower tooth root bending strength than metal, limiting the maximum torque; tooth width should be slightly narrower than the equivalent metal gear to reduce the risk of mechanical interference at the toe end. (2) Heat retention — plastic has low thermal conductivity; sustained high-speed, high-load operation causes thermal build-up that degrades the tooth surface; duty cycles must be limited at elevated ambient temperatures. (3) Dimensional change — thermal expansion and moisture absorption both change dimensions beyond metal equivalent; backlash must be set at the equilibrium operating condition, not the as-moulded dry-room condition.

Injection Moulding Plastic Bevel Gears

Plastic straight bevel gears are injection-moulded with straight-pull (or simple core-pull) moulds — the tapered conical tooth form allows axial ejection from the mould without an unscrewing mechanism (unlike helical gears). This simplifies the mould design and reduces tooling cost. Spiral bevel gears require more complex moulds with curved cavity surfaces, increasing mould cost. For most plastic bevel gear applications where the load is light and noise is moderate, straight bevel gears from injection moulds are preferred for their lower mould cost and faster production cycle.

Lightweight

POM and nylon bevel gears are 5–7× lighter than equivalent steel bevel gears. In hand-held power tools, this weight reduction reduces user fatigue. In battery-powered devices, the lower rotor inertia of the lightweight bevel gear reduces the motor's acceleration energy demand, directly extending battery life per charge cycle.

Non-Rusting

POM and nylon bevel gears do not rust — they are completely corrosion-resistant to the salt spray, humidity, and cleaning chemicals that destroy unprotected steel bevel gears. This non-rusting property is critical in food machinery, marine equipment, garden tools, and outdoor consumer products where steel bevel gears would require expensive stainless steel or surface treatment to maintain corrosion resistance.

Quiet Operation

Plastic bevel gears are significantly quieter than metal bevel gears — from the inherent damping of POM and nylon materials. In consumer electronics and household appliances where gear noise is a product quality signal to the user, the quieter plastic bevel gear improves the perceived product quality without the cost of adding acoustic enclosures. The spiral bevel variant is quieter still — typically 3–6 dB(A) quieter than the equivalent straight bevel at the same speed.

Low Cost at Volume

Injection moulding enables low-cost, large-volume production of plastic bevel gears — once the mould is made, each part is produced in seconds at minimal incremental cost. The standard M0.5 and M1 bevel gears in Korea Ever-Power's catalogue use existing mould tooling — no new tooling cost for standard sizes. This makes plastic bevel gears accessible for high-volume, cost-sensitive consumer applications.

Operates Without Lubrication

POM bevel gears can operate without lubrication when mating with metal pinions — the POM's intrinsic tribological properties provide adequate tooth surface lubrication in light-duty applications. This eliminates maintenance (no re-greasing) and contamination risk, making plastic bevel gears the preferred choice for food machinery, medical equipment, and sealed consumer product applications.

Power Tools

POM and nylon bevel gears in electric screwdrivers, angle grinders, cordless drills, and garden tools — transmitting motor torque from the horizontal motor shaft to the vertical drive shaft at 90°. The plastic bevel gear's lightweight contributes to the tool's balanced feel; its non-rusting properties suit outdoor garden tools; its quieter operation suits indoor power tools in noise-sensitive environments.

Automotive Applications

Nylon and POM bevel gears in automotive electric mirror adjusters, headlight levelling actuators, and dashboard instrument mechanism drives — wherever a small, lightweight 90° direction change is needed in a limited-access automotive interior location. The −40°C to +80°C operating temperature range covers typical automotive interior conditions.

Food Production Machines

POM bevel gears in food processing machinery — mixers, grinders, conveyor drives, and packaging machines. The dry-running capability eliminates lubricant contamination risk in food contact areas; the non-rusting property eliminates corrosion from food acids, salts, and cleaning agents; the quiet operation suits food processing environments where noise regulations are strictly enforced.

Consumer Electronics

Fine-pitch POM bevel gears (M0.25–M0.5) in camera lens focus and tilt drives, phone camera module tilt actuators, and small appliance 90° drive mechanisms. The standard M0.5 catalogue gear (GB05M016, 16T, OD 8.7 mm, bore 3.0 mm) covers most miniature consumer electronics bevel gear applications — available from Korea Ever-Power's stock without custom tooling.

Toys and Robots

ABS and nylon bevel gears in RC cars (front axle differentials), walking robot leg joints, and educational robot kits. The 1:1 ratio bevel gear pair is standard in toy differential mechanisms; the lightweight, low-cost, and self-lubricating properties match toy product design requirements exactly. The plastic bevel gear meets toy safety standards (no sharp edges, no toxic materials) inherently.

Medical Equipment

POM and PEEK bevel gears in medical instrument drives, surgical robot joints, and diagnostic equipment positioning stages. The dry-running, no-lubrication operation eliminates contamination risk in sterile medical environments; PEEK bevel gears can be steam-autoclaved at 134°C for repeated sterilisation cycles; the lightweight construction reduces the arm weight of surgical robots where surgeons hold the instrument continuously.

Should I choose straight or spiral bevel gears in plastic?

Straight bevel gears are the standard choice for most plastic bevel gear applications — simpler mould, lower tooling cost, adequate noise performance for most consumer and industrial applications. Choose spiral bevel gears when: noise is a primary concern (3–6 dB(A) quieter than straight bevel at the same speed); load is higher (spiral bevel's higher contact ratio gives better load capacity per unit size); or speed is higher (spiral bevel's gradual tooth engagement reduces impact loading at speed). Korea Ever-Power supplies both; the standard catalogue is straight bevel; spiral bevel is available on custom order.

What is the operating temperature limit of plastic bevel gears?

Korea Ever-Power's standard plastic bevel gears (POM/Nylon) are rated −40°C to +80°C for continuous operation — covering typical consumer electronics, automotive interior, food production, and general industrial ambient temperature ranges. For applications above +80°C, specify PPA (to ~120°C), PEEK (to ~250°C), or glass-fibre-reinforced PA66 (to ~130°C). Korea Ever-Power can supply plastic bevel gears in higher-temperature materials for under-hood automotive, oven equipment, and industrial high-temperature applications.

Can Korea Ever-Power supply matched plastic bevel gear sets (pinion + gear) at non-1:1 ratios?

Yes — Korea Ever-Power supplies matched plastic bevel gear sets in ratios 1:1, 2:1, 3:1, 4:1, and 5:1 at modules M0.5 and M1 from standard catalogue stock. For non-standard ratios or modules, custom matched sets are produced per customer drawing. Matched set supply ensures that the pitch cone angles, module, and pressure angle are geometrically consistent — mismatched bevel gear sets from different sources produce incorrect cone apex alignment and accelerated tooth wear at the misaligned contact zone. Contact Korea Ever-Power with your ratio and module requirement.

"We produce electric kitchen appliances and source POM straight bevel gears (M1, 16T, 1:1 ratio, GB1M016) from Korea Ever-Power for our motor-to-whisk 90° drives. Weight per gear: 2.3 g vs 18.1 g for the previous steel gear — critical for our hand-held product ergonomics spec. Noise at 0.5 m: 41 dB(A) vs 53 dB(A) for steel — well within our 50 dB(A) kitchen environment spec. Operating without grease: 5,000 operating cycles confirmed on life test at rated torque and speed without lubricant."

Kim Seon-woo  |  Kitchen Appliance Mechanism Engineer, Incheon Home Electronics Co.  ·  Q2 2026

"We manufacture food processing conveyors and specified POM bevel gear sets (M1.5, 20T, 2:1 ratio) from Korea Ever-Power for our 90° drive heads. Food contact approval: POM-C material certification accepted by our HACCP auditor. Corrosion test after 100 hours steam cleaning: no dimensional change, no surface degradation. Noise in production area: 46 dB(A) — below our food-grade noise standard. Zero re-greasing required — confirmed by 24-month field service review."

Lee Bo-ram  |  Food Conveyor Design Engineer, Gyeonggi Food Automation Co.  ·  Q4 2025