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KOBA-check® Sphere Plate

Characteristics of the KOBA-check Sphere Plate
Short-Term Stability
  • Distortion-free support with ball bearing mountings in prisms on a reinforcement plate

  • The arrangement of the ceramic spheres in the neutral plane ensures that no alterations in the gap between given spheres arise when there are positional variations in the measured volume (bowing of the sphere plate) and that their relative position to one another does not change.

  • Insulating handles and plastic protection to reduce thermal effects

  • Rigid underframe and assembly parts guarantee vibration free construction

Long-Term Stability
  • A special aging process guarantees long life and a high degree of dimensional stability.

  • Symmetrical form ensures no distortion when used at different temperatures.

  • Solid construction and purpose-built transport containers make warping or damage during transport or assembly virtually impossible.

  • The contact elements, embedded in the plate body, are protected from damage

  • Ceramic spheres give the contact elements high resistance to wear.

Contact Elements of the Sphere Plate
  • 30mm diameter ceramic spheres with a sphericity less then 0.15µm

  • Ring gage with a dimensional variation of 0.3µm (calibrated on request)

Accessibility of the Contact Elements
  • The special configuration of the ceramic sphere area allows free access to the equatorial area in tour sectors and scanning in hemispherical halves around the poles.

  • Drilled "voids" allow the measurement probe to be aligned at an angle to the plate within certain limits, without collision occurring.

  • In vertical operation, contact is possible from both sides of the sphere plate.

  • Screw-in insulating handles for easy maneuvering

  • Accessories allow mounting in various positions

  • Superfluous material is drilled out to reduce weight to a minimum

  • Vertical construction with accessories in the direction of the axis planes or the spatial diagonals. Horizontal construction parallel to the measuring table 35° angled arrangement with underframe parts

  • KOBA-check sphere plate and probe test unit calibration can be done by the appropriate laboratory, guaranteed traceable to the official length standard

Required Time for Monitoring
  • Quick set-up with easy to use assembly components

  • Short tempering time with manipulation using insulating handles

  • Three spatial axes are determined in one measurement cycle when positioned in one diagonal of the measured volume

Technical Data

Number of Spheres:25

Sphere Diameter:22µm



Hardness:> 1650 HV

Coefficient of Thermal Expansion:a = 11.5 x 10^-6 K_-1

Plate Body

Material:Gage steel, treated against surface corrosion

Coefficient of Thermal Expansion:a = 11.5 x 10^-6 K_-1

Ring Gage

Coefficient of Thermal Expansion:a = 11.5 x 10^-6 K_-1

Dimensional Variations:< 0.5µm
< 0.3µm on request (extra charge)

Probe Test Sphere

Coefficient of Thermal Expansion:a = 11.5 x 10^-6 K_-1

Dimensional Variation:< 0.15µm

Hardness:> 1650 HV

Ranges Supplied
  • 4 standard sizes in square form

  • Special sizes and designs at customer's request

  • Accessories for fastening the sphere plate on the measuring instrument table: adapter plate, additional lateral support, underfram elements for 35° tilt

  • Probe test unit

  • Sturdy aluminum storage cade

Size:620, 420, 320, 230

Dimensions620x620x24mm, 420x420x24mm, 320x320x24mm, 230x230x24mm

Weight28kg, 18kg, 11kg, 9kg

Max. Sphere Gage 532mm, 332mm, 240mm, 150mm

Nr. of Spheres25, 25, 25, 9

Data Analysis Software

Evaluation software is available for all artifacts, please contact us for details.

Applicable SIC Codes: 3423, 3545, 5049, 5084
Applicable NAICS Codes: 332212, 333515, 423490, 423830

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