mass calibration with robotic comparators · mass calibration with robotic comparators 2013 ncsli...

Mass Calibration with Robotic Comparators 2013 NCSLI Workshop and Symposium

Mettler Toledo

SPG Metrology

Mark Kliebenschädel

1

Content

Learning Objectives

Principle of a robotic comparator

Security

Accuracy & Performance

Influence of Cornerload

Dissemination

Productivity

2

Content

Learning Objectives


Security



Dissemination

Productivity

3

Learning Objectives

How to become a productive mass lab

How is dissemination carried out on a robotic

comparator

Understanding relevant factors for robotic

weighing

Set-up of ideal weighing process to improve

efficiency

How to improve the security of your

calibration process

4

Content

Learning Objectives


Security



Dissemination

Productivity

5

Principle of a Robotic Comparator

1. Mass Comparator Balance

2. 3-Axis Robotic System

3. Magazine

4. Indicator Unit

5. Robot Housing

6. Robot Arm

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Robotic Weighing Systems capable of measuring all classes from 50 µg to 20kg.

a107 (1g to 100g) a5XL (50µg to 5g) AX32004-M10 (1kg to 20kg)

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Depending on the type and accuracy, a window

range comparator is used. This requires the

loading of additional dial weights.

Robotic Systems switch weights automatically

according to the nominal load.

It allows calibration of weight set with different

nominal weights without interference

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Content

Learning Objectives


Security



Dissemination

Productivity

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Security

To minimize risks, many features are implemented into a robotic system

Optimized Robot Arm Speed Safety Doors / E-Stop

Carrier detection Weight detection Secure Data Management

Balance Position Sensor

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Security

In Mass Calibration a repetitive measurement is usually performed.

Potentially higher risk of "mixing up" or losing a weight, especially for

smaller weights.

Less risk if weights are calibrated on a robotic system

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Learning Objectives


Security



Dissemination

Productivity

Content

12


Balance stands separate to avoid possible vibrations

coming from the robotic system

Ball bearing technology allows precise positioning and smooth,

vibration-free movement

Weights experience less abrasion if handled by a robotic

system. Reference weights will remain longer within the

tolerance of their class

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No human influence /errors, such as imprecise

placement of the weight

Better performance and accuracy can be achieved with a robotic

system compared to a manual comparator

Possibility of setting a start delay for the

measurement allows the weights to acclimatize

Software considers drift of balance by using ABA /

ABBA method

Overnight measurements can be performed

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Content

Learning Objectives


Security



Dissemination

Productivity

15

Influence of cornerload

The cornerload is the deviation in the measurement value caused by eccentric loading of a

weight on to the weighing pan.

Robotic systems with fixed or with a so-called "LevelMatic" weighing pan are available.

Weight will be centered automatically to

the center of gravity. Eccentricity error is

negligible

Only 1. vs 1 comparisons possible

With a fixed weighing the weight has to be

centered/positioned very accurately.

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Influence of cornerload

Carrier of a5 Carrier and Inserts of a100 Carrier of a1000

Selecting best suitable carrier will prevent a minimum of eccentricity effect

To achieve best possible accuracy, the weight carrier principle is applied.

The carriers have different recesses with different diameters, or are

adjustable to the right size of the weights diameter.

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Content

Learning Objectives


Security



Dissemination

Productivity

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Dissemination

The dissemination method is used to calibrate

the unknown masses (weights set) by using

only one reference weight and working

downwards or upwards

If an asymmetrical scheme is chosen, for

instance 5g vs. 3g + 2g an automatic

correction is made to the measured value

Up to 3 weights can be loaded on to the

weighing pan. This is done symmetrically to

avoid eccentric load errors

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Dissemination

• The dissemination of a full weights set can be very time-

consuming and difficult to achieve if carried on a manual

comparator.

• To calibrate a decade (for example 1g to 100mg),

10 measurement groups are necessary.

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Content

Learning Objectives


Security



Dissemination

Productivity

Heusser Neweigh

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Productivity

Mettler Toledo USA

TROEMNER

NIST

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Productivity

Robotic comparators have been continuously improved over the

past years to perform more efficiently and productively, but still

fulfilling the accuracy needed to calibrate according to the

required uncertainties

Software able to measure several customer weight sets placed on the magazine.

Report for each customer is generated

Import of jobs possible while robot is still in progress

Optimum ergonomic location of the magazine for faster loading

Larger magazine sizes

Standards centering history

Sending of e-mails if measurement is completed, has started or aborts

IMPORT

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Productivity

Set-up of ideal weighing process can improve accuracy and efficiency

Performing Pre-Check – Nominal weight will be checked

prior to start of measurement

Acclimatize weight according table shown in OIML B.4.3

Choose number of repetitions recommended by the OIML C.4.3

Ideal Stabilization time of comparator is evaluated by

technician during installaton

History Specific Pause

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Summary

Robotic Comparators are not only used for maximum

throughput, also for maximization of security

Dissemination can be carried out easily on a robot

Robotic comparators allow the calibration of weights

starting from 50µg to 20kg for all weight classes

Many features are implemented to improve accuracy,

efficiency and productivity of a robotic system

Thank you !

Mettler Toledo

SPG Metrology

Mark Kliebenschädel

mass calibration with robotic comparators · mass calibration with robotic comparators 2013 ncsli...

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