Unlock Proven Secrets of TAC Series Ball Screw Bearings
Summary:
TAC series angular contact ball bearings are purpose-built for ball screw support in CNC machines, automation stages, and robotics. This guide explains where 25TAC, 35TAC, and 40TAC bearings fit best; how preload classes affect rigidity and speed; how to size TAC bearings for axial loads; and how to choose the right arrangement for precision and uptime. Includes quick selectors and product links to buy now or request plant pricing.
Table of Contents
- Introduction
- What Is a TAC Series Bearing?
- Preload Classes: Rigidity vs Speed
- Common Arrangements for Ball Screw Support
- How to Size TAC Bearings for Axial Loads
- Quick Selector: 25TAC vs 35TAC vs 40TAC
- Best-Fit Use Cases in CNC, Automation, and Robotics
- Featured Products (Buy Now)
- Mounting, Lubrication, and Setup Tips
- Common Failure Modes and Prevention
- FAQ
- Conclusion & CTAs
1) Introduction
Ball screw support bearings see predominantly axial load, require high stiffness for precision positioning, and must maintain preload stability at speed. TAC series angular contact bearings are engineered specifically for that job—offering high contact angles, matched-face accuracy, and factory-controlled preload. In CNC and robotics, the right TAC selection improves servo responsiveness, reduces backlash, and stabilizes heat growth effects.
2) What Is a TAC Series Bearing?
TAC bearings are super-precision angular contact ball bearings designed for axial load dominance with minimal axial play. They typically feature:
- High contact angle (commonly ~60° class for screw support): maximizes axial capacity and stiffness.
- Ground raceways and faces: ensures stack-up accuracy in pairs/sets.
- Preload classes: factory-set preload for predictable rigidity and thermal behavior.
- Separable/non-separable variants and options for seals/shields depending on series.
3) Preload Classes: Rigidity vs Speed
Preload is the most important tuning lever. It dictates static stiffness, running torque, heat generation, and ultimately speed capability.
- Light (L) preload: best for higher speed, lower heat. Good for fast, low-thrust axes with modest cutting forces.
- Medium (M) preload: balanced rigidity/speed. Often the default for general CNC axes and automation stages.
- Heavy (H) preload: maximum stiffness and positional stability under varying axial loads. For heavy cutting, high inertial loads, or vertical axes where gravity/overturning moments add preload.
Rule of thumb: Increase preload for rigidity and disturbance rejection; decrease preload for speed and lower thermal rise. Validate with your duty cycle and servo tuning plan.
4) Common Arrangements for Ball Screw Support
- DB (Back-to-Back): Wider spread of contact angle lines; excellent tilting rigidity and thermal stability. Most common at the driven (fixed) end of a ball screw.
- DF (Face-to-Face): Better for misalignment accommodation, slightly lower moment stiffness; used in select layouts.
- DT (Tandem): Two (or more) bearings share axial load in one direction. Often combined as DBT/DFT for bi-directional axial capacity and higher thrust rating.
Typical ball screw support: Fixed end uses a DB or DBT TAC set (preloaded) for positioning; support end uses a floating bearing (deep groove or cylindrical roller) to allow thermal growth.
5) How to Size TAC Bearings for Axial Loads
Follow a practical, conservative process:
- Determine axial load envelope: include cutting thrust, acceleration/deceleration forces, gravity (vertical axes), and shock factors. Define peak and RMS values.
- Select preload class: based on required positioning stiffness and servo bandwidth. Heavier preload for heavy cuts/vertical axes; lighter for high-speed pick-and-place.
- Choose arrangement: DB for most fixed ends; add tandem (DBT) if thrust ratings or rigidity need a boost.
- Check static safety: Ensure the combined static capacity exceeds maximum axial shock load with margin.
- Check dynamic life: Use equivalent axial load and desired life (e.g., 20,000–30,000 hours) to verify dynamic rating sufficiency.
- Validate speed/temperature: Confirm cage, lubrication, and preload alignment with top speed targets; adjust preload down or lubrication up if running hot.
Tip: For compact robots and light CNC axes, 25–35 mm bore TAC sizes cover most needs; for large gantries and heavy-duty machine axes, 40 mm and up is common.
6) Quick Selector: 25TAC vs 35TAC vs 40TAC
- 25TAC (e.g., 25 mm bore): Compact/high-precision axes, small/medium CNC stages, robotics joints with moderate thrust and high speed.
- 35TAC (35 mm bore): General-purpose CNC X/Y axes, medium gantry stages, heavier collaborative robot joints; balanced stiffness and life.
- 40TAC (40 mm bore and up): Vertical axes, heavy cutting thrust, larger gantries; prioritize stiffness and axial capacity over peak speed.
Preload pairing: Start with Medium preload for general CNC; use Heavy for vertical Z or high-thrust milling; Light for high-speed automation pick-and-place.
7) Best-Fit Use Cases in CNC, Automation, and Robotics
a) CNC Machine Axes
- X/Y axes: 25–35TAC with Medium preload in DB arrangement for microns-level positioning without excessive heat.
- Z axis (vertical): 35–40TAC with Heavy preload in DB or DBT to counter gravity and cutting thrust; robust stiffness for step rejection.
b) Automation & Gantry Stages
- High-speed pick-and-place: 25TAC Light preload for lower torque and heat, preserving servo agility.
- Precision assembly/inspection: 25–35TAC Medium preload for stability under small but frequent direction reversals.
- Actuated linear axes in arms and wrists: 25–35TAC depending on load; Medium preload for balanced rigidity vs thermal rise.
- Heavy payload or long-reach stages: 35–40TAC Heavy preload and DBT for maximum positioning firmness.
8) Featured Products (Buy Now)
-
25TAC62CSUHPN7C – Compact, high-precision screw support for fast axes and robotics.
Buy 25TAC62CSUHPN7C → -
35TAC72CSUHPN7C – General CNC/automation workhorse; ideal X/Y axes and medium-duty gantries.
Buy 35TAC72CSUHPN7C → -
40TAC100CSUHPN7C – High-thrust vertical axes and heavy-duty stages; maximize stiffness and life.
Buy 40TAC100CSUHPN7C →
Tip: For bi-directional thrust and highest rigidity, purchase bearings in matched sets for DB/DBT arrangements and specify preload class per axis.
9) Mounting, Lubrication, and Setup Tips
- Shoulders and fits: Machine square seating faces; use recommended interference/transition fits to prevent creep while avoiding excessive hoop stress.
- Pressing: Apply mounting force through the ring being fitted (inner for shaft, outer for housing). No hammering.
- Preload integrity: Do not swap components between matched pairs/sets; keep orientation marks.
- Lubrication: Precision grease for most CNC/robot axes; consider oil mist/air-oil for very high speed applications. Avoid over-greasing to limit heat.
- Commissioning: Run-in at incrementally higher speeds, monitor temperature and current draw, then finalize servo gains.
10) Common Failure Modes and Prevention
- Thermal growth/preload shift: Validate preload vs speed; allow expansion at the support end of the screw.
- Contamination: Maintain clean assembly; use end caps/seals; ensure positive pressure purge where possible.
- Misalignment: Verify squareness/runout; DB sets are less tolerant of squareness errors—measure and correct.
- Over-greasing: Leads to heat and torque spikes; follow manufacturer fill guidance.
- Impact/handling damage: Use proper tools; store bearings in original packaging until installation.
11) FAQ
Q: Which preload should I pick for my CNC axis?
A: Start with Medium preload for general X/Y. Use Heavy for vertical Z or heavy cutting thrust. Choose Light for high-speed, low-load automation.
Q: Do I need tandem (DT) bearings?
A: Use tandem if your axial thrust rating requirement exceeds a single DB set, or if you want extra stiffness margin. Combine as DBT for bi-directional thrust.
Q: Can TAC bearings run very fast?
A: Yes, but speed is limited by preload, lubrication, and cage design. For top speed targets, reduce preload and use appropriate oil-air lubrication.
12) Conclusion & CTAs
Choose 25TAC/35TAC/40TAC based on your axis thrust, stiffness target, and speed plan—then match preload to your application dynamics. Use DB on the fixed end and verify thermal strategy at the floating end for long, quiet life.
For volume needs: Request bulk/contract pricing for plants.