This page now separates the prismatic joint's one-axis kinematic constraint from a declared ideal Coulomb-friction worksheet. It does not predict clearance, accuracy, binding, wear, lubrication regime, life, actuator demand or safe design.
Prismatic-Joint Friction Explorer
Enter declared normal load, added guide preload, friction coefficient and sliding speed. The animation preserves a fixed guide and translating carriage while the worksheet reports only the declared ideal friction and power identities.
Equation Used
- The joint coordinate is one-axis translation; the animation prescribes it independently of the force calculation.
- Declared normal load W and added guide preload G are summed as N=W+G for this ledger.
- The declared coefficient mu is treated as constant and friction opposes sliding.
- Power uses declared speed converted from mm/s to m/s.
- Load distribution, moments, contact geometry, clearance, compliance, static friction, stick-slip, lubrication, temperature, contamination, wear, drive efficiency, acceleration, duty cycle, ratings, stops, life and safety are excluded.
Replaces universal tolerance, performance and field-service claims with a declared ideal Coulomb ledger and one-axis connected translation.
A prismatic joint contributes one translational coordinate
Modern Robotics and the University of Illinois describe a prismatic joint as a one-degree-of-freedom joint whose coordinate is translation along its axis. The animation therefore keeps the carriage orientation fixed while its position changes along one straight guide.
The friction worksheet is separate from that kinematic fact and does not determine the motion.
Use this page only to audit declared friction arithmetic
The worksheet adds two declared normal-force terms, multiplies by a declared coefficient, converts newtons to pounds-force and multiplies by declared speed for ideal dissipated power.
It cannot size or select a guide or actuator, set a gib, predict accuracy or life, or diagnose a real slide.
State every quantity as a declared input
NASA's tribology reference states the basic coefficient identity mu=F/L; real coefficients and resistance depend on the actual interface and operating state.
A transparent declared-input example
For W=500 N, G=100 N, mu=0.080 and v=100 mm/s, combined normal load is 600.0 N, ideal friction is 48.0 N or 10.79 lbf, and ideal friction power is 4.8 W.
No clearance, drive-force margin, thermal result or service-life conclusion follows.
A constant-coefficient ledger is not guide performance
THK notes that guide resistance depends on guide type, preload, lubricant viscosity and applied load, and that preload raises resistance. A real assessment also needs load distribution, moments, geometry, tolerances, compliance, acceleration, environment, duty cycle and manufacturer ratings.
The former universal clearances, finishes, speed bands, material limits, life claims, named deployments, worked example, diagnostics and field-adjustment advice are removed because they were not established for one documented joint.
Prismatic-joint ledger questions
Does a prismatic joint guarantee zero real rotation?
The ideal kinematic joint has one translational degree of freedom; real clearances and compliance are not calculated here.
Does speed determine mu in this calculator?
No; mu is declared independently.
Does G represent a particular gib or rail preload?
No; it is only an added declared normal-force term.
Can this size a drive or guide?
No.
Prismatic-joint and friction references
- Northwestern, Modern Robotics: a prismatic or linear joint is a one-degree-of-freedom joint.
- University of Illinois, Robotic Systems — Kinematics: its coordinate is translation along the joint axis.
- NASA, Friction, Wear, and Lubrication Fundamentals: mu=F/L for declared friction force and normal load.
- THK LM Guide friction FAQ: resistance depends on guide type, preload, lubricant viscosity and applied load.
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