Standards for 3-D coordinate metrology

Check your coordinate measuring machines with the standards from Kolb & Baumann

The periodic monitoring of hand-held or computer-controlled coordinate measuring machines is carried through on the basis of calibrated mechanical test bodies.
By suitable selection and combination of different test bodies such as ball, step gauge block and ball plate and their arrangement, the entire measuring volume or certain partial measuring volumes can be covered according to the typical workpiece size and the inspection can be adapted to their most important measuring task. The sequence control is uniform according to the nominal data of the test piece. Numerical and graphical evaluation is carried through with a uniform program for each type of test specimen and evaluated by qualified personnel. Summarized parameters provide an overview of the current accuracy status and long-term trends. In this way, the use of coordinate measuring machines can be optimized and their downtime minimized at low cost. Fig. 1: KOBA-check ball plate in horizontal configuration with insulating handles and probe test unit. In order to meet the increased requirements for inspection of coordinate measuring machines, Kolb & Baumann has supplemented its product range (including KOBA-step) with the KOBA-check ball plate. This embodies almost all the properties required of a test unit for monitoring CMMs

Step Gauges for calibration and monitoring of coordinate measuring machines

In industrial metrology for geometric quantities, tactile probing linear scales have an important role as reference standards.
They have gained particular importance in the calibration and monitoring of one-, two- and three-coordinate measuring machines with mechanical probing. The approach of using the length measurement deviation for the acceptance and continuous monitoring of coordinate measuring machines, in conjunction with tactile probing test specimens, has proven to be a meaningful and economical method. Here, the Step Gauge offers universal applicability and maximum flexibility. The great importance of physical measuring standards in metrological traceability, calibration and monitoring results from, among other things, the VDI/VDE 2617 series of guidelines and the DIN EN/ISO 10360 standards. These technical regulations prove the outstanding suitability of linear scales for the monitoring of measuring and test equipment, which is absolutely necessary in the context of quality assurance.

The Step Gauge Concept
The most precise standard for representing the measurand length is the gauge block.
The most precise standard for representing the measurand length is the gauge block. This is also still in use for calibration. Mostly in use of a so-called gauge block harp. The disadvantage here is the very limited number of possible measuring lengths and length steps. The gauge block is considerably more complex in application, since each nominal dimension must be measured individually in the measuring volume of the CMM. This is where the step gauge concept comes into play. In the step gauge, a large number of small gauge blocks (measuring tines) are arranged along the neutral fiber in a rigid support body. The distance between the individual gauge blocks allows all measuring surfaces to be probed.

All measuring surfaces are positioned parallel to each other along the measuring line. This makes it possible to link any two measuring surfaces to represent a length. Due to the opposite orientation of the measuring surfaces, external, internal and step dimensions can be measured along the measuring line. The number of lengths that can be measured increases disproportionately with the number of available measuring surfaces. For example, a KOBA-step® of nominal length 1,020 mm with its 26 probing elements, corresponding to 52 measuring surfaces, provides a total of 1,326 possible measuring lengths with just 52 probing operations.

Step Gauge KOBA-step®

One-dimensional test specimen with plane-parallel measuring surfaces along a measuring line.

Field of application:

Calibration, monitoring and traceability of tactile coordinate measuring machines.
Monitoring of height measuring instruments
- versions in nominal lengths from 420 mm to a maximum of 2,020 mm
- special lengths on request
- 20 mm pitch (10 mm on request)
- meets all requirements of ISO 10360 and VDI/VDE Guideline 2617
- proven, very good long-term stability
- practical accessories for effective handling and optimization of calibration procedures
- optional PTB, DAkkS or KOBA calibration
- proven and instrument-independent evaluation software available

Step Gauge KOBA-step® mini

optimized for use with small-volume, tactile CMMs, e.g. multisensor devices
nominal lengths 210 mm and 310 mm
10 mm grid
optional PTB, DAkkS or KOBA calibration
proven and instrument-independent evaluation software available

Ball Bar

Special requirements are placed on the monitoring procedure of large coordinate measuring machines, where at least one axis is longer than two meters:
• assessment possibility for the entire measuring volume with sufficiently fine subdivision
• detection of the effect of where possible all error components, as well as of the touch probe system, also for CMMs with numerical error correction
• conformity of the determined parameters to existing standards and guidelines and thus easy interpretability
• general good/bad statement
• connection to the SI unit meter
• easy handling and fast mounting
• easy calibration
• short set-up times
• easy handling due to maximum element length of 1,800 mm with low weight
• different lengths and pitches
• constant axial force on the ball-distance tube joint
• corrosion-resistant due to ceramic balls and stainless steel distance tubes
• alternatively carbon fiber distance tubes with coefficient of expansion approaching

Design Features:
The supporting body consists of low weight foamed CFKGFK aluminum box section, whose outstanding features are high rigidity and good vibration absorbtion. The number of individual elements depends on the overall length. These are held together force-fit by connecting elements. The probing elements are ceramic balls that are connected to the receptacles in the base body by a spring element. This spring element provides the freedom of movement in the axial direction required for perfect contact between the ball and the distance tube. The lined-up rods and balls are impinged on by a clamping unit with reproducible force in the axial direction and are supported at the opposite end on a fixed abutment. This avoids length changes caused by different pretensioning forces

Handling: Due to the well thought-out design, the assembling of the completely demounted test specimen by one person takes approx. 20 minutes.
Moving the test specimen within the measuring volume can be accomplished within a few minutes.

Calibration:

The calibration of the individual measuring sections can be carried throuh by the user on an accurate coordinate measuring machine of normal size. This reduces the calibration costs considerably. For the purpose of calibration only the first supporting element is used. A small number of measuring sections, according to the size of the measuring instrument, are mounted on this with a clamping unit. The respective pairings (e.g. ball1-rod1-ball2 / ball2-rod2-ball3, etc.) are measured and the values for the ball center distances are documented in a calibration certificate

KOBA - Ball Bar

One-dimensional, demountable test specimen with spherical probing elements.

Field of application:

Monitoring of large-volume coordinate measuring machines e.g. column and gantry measuring machines.
Inspection of optical-tactile measuring systems such as laser trackers
- size from 3 to 8 m nominal length
- special sizes and individual pitches can be realized
- ceramic probing elements
- distance tubes in steel or carbon fiber
- demountable
- very good reproducibility of measuring lengths
- low weight
- optional PTB, DAkkS or KOBA calibration certificate
- proven, user-friendly and gauge-independent evaluation software available

Ball bars & taper bars

The field of application of ball bars is in the calibration and monitoring of medium-sized coordinate measuring machines.
Due to our newly developed swivel fixture for the ball bars, it is possible to position the bars from 0-90 degrees on the CMM in a user-friendly and dimensionally stable way.

KOBA sphere beam

The KOBA sphere beam is a non-demountable sphere beam for monitoring and calibration of medium-sized CMMs. Ceramic spheres as probing elements, which are fixed in a stable position in a specially designed support, represent the long-term stable measuring lengths. Nominal lengths from 1,500 mm to 2,500 mm, with customer-specific pitches and ball diameters are available. Positioning of the KOBA sphere beam in a broad range within the volume of the CMM can either be made by using two light tripods in CFC or by a torsion-proof base on which a swivel arm is mounted.

Design Features:
The carrying body consists of an ultra-high-modulus CFC integral profile of highest possible fiber volume. This CFC profile is extremely rigid and dimensionally stable due to its design and the manufacturing technology used. To prevent dimensional changes caused by humidity, the load-bearing body is additionally equipped with a water-vapor-proof coating.

Sphere plate KOBA-Check

The sphere plate represents a two-dimensional measuring standard for calibration and monitoring of coordinate measuring machines. The test specimen fulfills the requirements of ISO 10360 and VDI /VDE guideline 2617 for a calibration standard for the monitoring of CMMs. Special measuring strategies allow a reliable statement regarding the achievable measuring accuracies for the CMM.

KOBA-check sphere plate characteristics Short-term stability:
Distortion-free support with ball bearing mountings inprisms 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. lnsulating handles and plastic protection to reduce thermal effects. Rigid underframe and assembly parts guaranteevibrationfree construction.

Probe Test Unit

Probe test unit for use in horizontal and vertical position of the ring gauge

ceramic sphere with Ø 30 mm and sphericity < 0,15 µm

setting ring with form deviation < 0,3µm (calibrated on request)

Opto-tactile Stepped Standards

Due to technical progress, the step standard has become one of the standard standards in optical and optical-tactile metrology.

The field of application of the Optical Tactile Step Standards is in the calibration and verification of triangulation laser scanners, laser focus measurement systems and fringe projection systems.

Opto-tactile Stepped Standards

Calibration standards based on gauge blocks with diffuse reflecting or shiny measuring surfaces. Made entirely of carbide and therefore corrosion-resistant. Customer-specific designs are available within wide limits.

Field of application:
Optical length and coordinate measuring systems such as

Triangulation laser scanners
Laser focus measuring systems
Fringe projection systems

Sphere Standards

Measuring balls with diffuse reflecting surface in various designs.
The balls are made of carbide with a scratch- and corrosion-restistant surface that also allows tactile probing.

Field of application:
Optical form and CMM’s such as

Triangulation laser scanners
video measuring systems
Fringe projection systems

3D Calibration Standards

Test specimen according to VDI/VDE 2634 made of optically cooperative ceramic materials.
The specially selected materials allow optical and tactile measurements and thus the direct linking of the two measuring principles.

Field of application:
optical 3D CMM’s such as

Fringe projection systems
3D CMM’s with optical touch probes

KOBA optima 2

System for monitoring of photogrammetry and theodolite systems

Properties

high short- and long-term stability
coefficient of thermal expansion close to zero
easiest handling
low weight
VDI/VDE 2634 compliant
DAkkS-calibrateable standard

Ball Cube

The Ball Cube offers a not inconsiderable cost-saving potential for the user in the field of test equipment monitoring.

high short- and long-term stability
very low coefficient of thermal expansion
easiest handling
low weight
fast measuring procedures
cost-effective calibration
good price-performance ratio
evaluation software

Ball Cube KOBA-Q3

Field of application

The Ball Cube KOBA-Q3 offers 28 lengths, which provide meaningful results regarding the measuring accuracies for volumetric measurements, especially when using star or swivel probe systems.
Very short measuring cycles allow monitoring checks without disturbing the availability of the CMM.

Design features

extremely dimensionally stable truss construction made of CFC tube with angular joints of stainless steel
the use of high-modular carbon fibers results in maximum rigidity at low weight
the specially manufactured CFC tubes are free from variation in lenght caused by humidity
the material combination guarantees a low coefficient of thermal expansion
the probing elements for tactile probing are high-precision ceramic balls made of Al2O3; for optical probing diffuse matt carbide balls or balls made of optically cooperative ceramic are available

Technical data:

nominal size 300 x 300 x 300 mm 400 x 400 x 400 mm 600 x 600 x 600 mm
nominal measuring lengths 300 / 424 / 520 mm 400 / 566 / 693 mm 600 / 849 / 1039 mm
ball-Ø 30 mm (others on request)
Mass approx. 5 kg approx. 6 kg approx. 7 kg

Get in contact with us.

Christian Bartel
Tel.: +49060213 463-15
christian.bartel@koba.de

Our manufacturing with unique precision technologies

Our strength lies in complete solutions. We manufacture your high-precision products from saw cutting to finish machining in the 0.0001 mm range, including comprehensive quality control.

We manufacture the right parts individually for your application.

Our range of services includes:
– Milling
– Vibratory finishing
– Rough grinding
– Surface grinding
– Lapping
– Hand Lapping