Gear and Rack
Why choose us
Incoming material and process control:
Racks are cut from S45C and 42CrMo and go through high-frequency quench or carburizing quench to HRC48–60°, with four-side and tooth-surface grinding applied on the ground grades. Hardness is the first value to verify on the goods you receive.
Tolerance and accuracy verification:
Ground racks are supplied to DIN6-8 with error as low as ±0.01mm/m, under 0.03 mm across a 3 m travel, and hole positions and overall length are checked against the drawing before the parts are packed for shipment.
Matching components and assemblies:
Rack, pinion, motor drive gear, support and gear box are quoted together, so module and pitch are matched and the gear box ratio is confirmed before anything is cut, which removes the mismatch that makes a new drive run rough.
Engineering and quotation response:
Send travel length, module, tooth form and load. You get back a rack and pinion combination with drawing dimensions confirmed, the mounting hole positions you asked for, and the dedicated fasteners quoted with the set.
A gear rack is a straightened pitch circle: meshed with a pinion it converts rotation into linear travel, and back again, at the load and the positioning accuracy the axis needs. On a 3 m gantry the rack decides repeatability long before the servo does; on a lifting column it decides how much thrust the pinion can push through each tooth without spalling. Spur or helical, ground or milled, the choice follows the same numbers: accuracy class, module, and tooth load.
How to choose a gear rack
Ground or milled comes first. A ground rack — four-side and tooth-surface ground — reaches DIN6-8 with error as low as ±0.01mm/m, so specify it where the rack is the last error source in the loop. Precision-milled racks cost less and handle general travel, indexing and non-cutting motion just as well.
Tooth form second. Straight teeth carry load with no axial reaction, so a plain spur rack and pinion suits single-axis drives and keeps the bearing arrangement simple. Helical racks hold more teeth in mesh at once, so they run smoother and quieter at the same load, and they push an axial force back into the pinion bearing — plan the gear box and housing for it instead of finding out in the field.
Third, module and pitch set both the ratio and the tooth load. Module 1.5–12 covers this range: small module for light, fast axes, large module where the pinion has to pass heavy torque at low speed. Motor drive gears are catalogued from 1.25 module, so the pinion can be quoted together with the rack. Pinion and rack must share module and pitch, and the gear box output has to accept the tangential force that comes back from the mesh.
Material and hardness last. Choose nylon models where low noise dominates, alloy steel racks for heavy-load duty. The steels used are S45C and 42CrMo, high-frequency quenched or carburizing quenched to HRC48–60°, which is what stops tooth flanks wearing into a backlash problem after a few years in service.
Gear rack series overview
The gear rack range at HLTNC splits by tooth form and material rather than by machine size.
| Series | Structure | Accuracy and load notes | Typical use |
|---|---|---|---|
| Spur (straight) rack | Straight teeth in S45C or 42CrMo, milled or four-side ground | No axial reaction; HRC48–60°; DIN6-8 on ground grades | Single-axis machine travel, router and gantry X/Y drives |
| Helical rack | Angled teeth, more teeth in mesh | Smoother and quieter at equal load; axial force to allow for | Higher-speed gantries and machine tools |
| Nylon rack | Polymer tooth form | Selected for low-noise duty rather than heavy load | Light, quiet axes and indexing fixtures |
| Gear box with motor drive gear | Aluminium alloy cast housing, direct motor coupling, long or short shaft | Pairs a pinion of the same module to the rack; ratio interchangeable | Servo or stepper axes needing torque multiplication ahead of the pinion |
Key gear rack specifications
- ▪Module 1.5–12 across the rack range; motor drive gears are catalogued from 1.25 module so a matched drive gear can be quoted with the rack.
- ▪DIN6-8 accuracy class on ground racks, with error as low as ±0.01mm/m — over a 3 m travel that is under 0.03 mm of rack error.
- ▪Hardness HRC48–60° after high-frequency quenching or carburizing quenching; base steels are S45C and 42CrMo.
- ▪Four-side grinding plus tooth-surface precision grinding on the ground grades.
- ▪20,000 hours of stable operation is the design target the material and the hardening route are chosen against.
- ▪Lengths and mounting hole positions are produced to drawing, with dedicated fasteners supplied to prevent breakage at the joint.
Applications and matching parts
Automation equipment, CNC machine tools, intelligent logistics equipment and industrial robots are the main users, covering lifting, translation and indexing moves. The gear box is the part that makes such a drive work: aluminium alloy casting keeps the housing light, a direct coupling between motor and gearbox cuts the noise and vibration a belt or an extra coupling stage would add, and the integrated motor interface takes servo or stepper input without an adapter. Shafts and spirals are cut long or short, and the internal ratio can be changed for a different job instead of replacing the unit.
Quote the gear rack, the pinion and the support in one enquiry. Motor drive gears are machined on high-precision equipment to a matching accuracy that keeps transmission accurate and cuts power loss, and their treated surfaces lower friction so the drive runs quietly. Buying them as a set removes the module or pitch mismatch that is the usual reason a rack drive runs rough from the first cut.
Rack and pinion backlash is set at assembly and then drifts with wear, so re-read it whenever the axis starts leaving witness marks. Set mesh clearance deliberately: too little binds the drive, too much rounds the tooth flanks. Gear box cooling and lubrication belong in the same sizing pass, not in later troubleshooting.
Quality control you can verify
Tooth hardness is the first number to check, because HRC48–60° confirms the hardening route was applied rather than only specified, and it is measurable with a hardness tester on delivery. Ground racks are supplied to the DIN6-8 class and the ±0.01mm/m figure, both re-checkable on a granite surface. Motor drive gears ship with an inspection certificate. Because racks and gear boxes are machined to drawing, verify hole positions and overall length against that drawing before assembly; four-side and tooth-surface grinding records apply to ground grades only. Ask for these documents at quotation stage and the gear rack specification stops reading as a claim.