Reciprocating #E - Internal Manual

General Presentation

All the load is applied on the 4 external miniature linear guides.
The inner linear guide and the self-adjusting bearing are translating rotation into reciprocating motion but are not subjected to vertical load.

Miniature Linear Guides

Specifications
Default Reciprocating:
Part Number
Dynamic Load Rating (N)
Static Load Rating (N)
BM126049
1500
2500
BM126051
1500
2500
Load Rating & Rated Life
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The linear bearing load calculation sheet available in the customer manual was calculated using the following parameters and formulas:
  • P1(max) = 1500N (as per misumi Dynamic Load rating)
  • X = 50mm (Center of the 4 screws holding the carriages)
  • Y = 36mm (Center of the 4 screws holding the carriages)
  • W (Max applied load for that position to be within the Load rating):
      • W=P1(max)14+X02X+y02YW = \frac{P_{1(\text{max})}}{\frac{1}{4} + \frac{X_0}{2X} + \frac{y_0}{2Y}}

Reciprocating extreme use case limits

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  • X0 = 15mm (max stroke length: 30mm, X.Position=0)
  • Y0 = 18mm
X0 (Max position in X, mm)
Y0 (Max position in Y, mm)
W (Max applied load for that position to be within the Load rating)
15
18
2308
Centered in X, Y at the extremity, the maximum load is 2300N
Rated Life
The linear bearing rated life calculation sheet available in the customer manual was calculated using the following parameters and formulas:
L=((C/P)3)∗50L = ((C / P) ^ 3) * 50
  • L : Rated Life (km)
  • C : Basic Dynamic Load Rating (N)
    • Dependent on the linear bearing used
  • P : Applied Load (N)
    • Using the Pmax calculated previously to determine the maximum rated life of the bearing under the highest load.
 

Self-Adjusting Ball Bearing

Rtec: BM121020
McM: 6660K11
Manufacturer: FAG
Item Number: 108-TVH
  • Type of lubrication:
    • Grease
    • Oil
  • Radial Load Capacity:
    • Static: 560N
    • Dynamic: 2750N
  • Axial Load Capacity:
    • Calculation needed
  • Rated life:
  • Rotational speed:
    • Reference: 27.000RPM
    • Limit: 39.000RPM
  • Temperature Range:
    • Min: -30°C
    • Max: +120°C
 
2,750 N Basic dynamic load rating, radial
C 0r 560 N Basic static load rating, radial
Rotational speed:

Regular Maintenance

Lubricate the Linear Bearings

Grease type

Filled with Lithium soap based grease (Multemp Grease PS2 by Kyodo Yushi Co., Ltd.).
Property
Typical Value / Feature
Thickener
Lithium soap
NLGI Grade
2
Base oil type
Synthetic + mineral blend
Base oil viscosity (40 °C)
≈ 15 mm²/s
Operating temperature range
−50 °C → +130 °C
Application focus
High-speed precision bearings, linear carriages
Characteristics
Low torque, low noise, oxidation stability, good water resistance
Preferably use this grease reference or search for a compatible Lithium soap based grease replacement available (EMEA: SKF LGLT2).

Grease application

  • Wipe off all old grease and debris from the carriage and rail using a clean, lint-free cloth.
  • If you’re changing grease type (e.g., from MULTEMP to SKF LGLT 2), flush out as much of the old grease as possible with a mild solvent (isopropyl alcohol or mineral spirit), then dry completely.
  • Place a small amount of grease at one of the sides of the carriage
  • Place the carriage back onto the rail.
  • Move the carriage slowly back and forth along its full stroke several times to distribute grease evenly across the ball raceways.
 

Advanced Maintenance

Replace the Linear Bearings

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Refer to the specific assembly drawing for the module to identify the correct Linear Guide part number. Always order replacement components using the exact part number listed on the drawing or bill of materials (BOM) to ensure compatibility and maintain alignment accuracy.

Bearing Replacement Criteria

Once the Rated Life of the linear bearings has been reached, or if you observe any of the following symptoms, the bearing and its rail must be replaced as a matched pair:
  1. Abnormal Noise — grinding, squealing, or clicking sounds during motion.
  1. Increased Friction — noticeable resistance or uneven movement along the stroke.
  1. Excessive Play or Looseness — detectable vibration or backlash in the axis.
  1. Surface Damage — visible scoring, pitting, or rust on the rail or bearing blocks.
  1. Motion Irregularity — sticking or non-uniform linear motion, even after cleaning and lubrication.
  1. Leakage of Lubricant or Contamination — accumulation of debris or oil leakage from bearing seals.
  1. Temperature Rise — bearing housing running unusually hot under normal operating load.

Bearing Replacement Procedure

  • Remove the old bearing assembly
    • Slide the carriage off the rail carefully to avoid scratching the raceways.
    • Remove all rail mounting screws and lift the rail vertically from the base.
  • Clean the mounting surfaces
    • Moisten a lint-free wipe with isopropanol (IPA) — do not soak.
    • Wipe the mounting surfaces in one direction (not circular) to remove oil, dust, or debris.
    • Verify that both the mounting face and the pins are free of burrs, scratches, or residues.
    • Blow off any remaining solvent with clean, dry compressed air.
  • Install the new rail
    • Place the rail gently on the installation side of the base.
    • Align the rail precisely against the alignment pins.
    • Insert and lightly tighten all screws while maintaining rail contact with both pins.
  • Final tightening
    • Using a calibrated torque wrench, tighten the screws to the specified torque in a center-out pattern to distribute load evenly.
      • Start by lightly tightening the center screw(s) first.
      • Then alternate outward toward both ends (left–right–left–right).
        • SPN
        Tightening Screw
        Tightening torque (N.m)
        Default Reciprocating
        4-40 (comparable to M3)
        1.0
    • Confirm that the rail sits flush across its full length before completing the tightening sequence.