Mass Calibration with Robotic Comparators 2013 NCSLI Workshop and Symposium. Mettler Toledo SPG Metrology Mark Kliebenschädel

Transcription

1 Mass Calibration with Robotic Comparators 2013 NCSLI Workshop and Symposium Mettler Toledo SPG Metrology Mark Kliebenschädel

2 Content Learning Objectives Principle of a robotic comparator Security Accuracy & Performance Influence of Cornerload Dissemination Productivity 1

3 Content Learning Objectives Principle of a robotic comparator Security Accuracy & Performance Influence of Cornerload Dissemination Productivity 2

4 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 3

5 Content Learning Objectives Principle of a robotic comparator Security Accuracy & Performance Influence of Cornerload Dissemination Productivity 4

6 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 5

7 Principle of a Robotic Comparator 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) 6

8 Principle of a Robotic Comparator 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 7

9 Content Learning Objectives Principle of a robotic comparator Security Accuracy & Performance Influence of Cornerload Dissemination Productivity 8

10 Security To minimize risks, many features are implemented into a robotic system Balance Position Sensor Optimized Robot Arm Speed Safety Doors / E-Stop Carrier detection Weight detection Secure Data Management 9

11 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 10

12 Content Learning Objectives Principle of a robotic comparator Security Accuracy & Performance Influence of Cornerload Dissemination Productivity 11

13 Accuracy & Performance 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 12

14 Accuracy & Performance Overnight measurements can be performed No human influence /errors, such as imprecise placement of the weight Possibility of setting a start delay for the measurement allows the weights to acclimatize Software considers drift of balance by using ABA / ABBA method Better performance and accuracy can be achieved with a robotic system compared to a manual comparator 13

15 Content Learning Objectives Principle of a robotic comparator Security Accuracy & Performance Influence of Cornerload Dissemination Productivity 14

16 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. 15

17 Influence of cornerload 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. Carrier of a5 Carrier and Inserts of a100 Carrier of a1000 Selecting best suitable carrier will prevent a minimum of eccentricity effect 16

18 Content Learning Objectives Principle of a robotic comparator Security Accuracy & Performance Influence of Cornerload Dissemination Productivity 17

19 Dissemination The dissemination method is used to calibrate the unknown masses (weights set) by using only one reference weight and working downwards or upwards Up to 3 weights can be loaded on to the weighing pan. This is done symmetrically to avoid eccentric load errors If an asymmetrical scheme is chosen, for instance 5g vs. 3g + 2g an automatic correction is made to the measured value 18

20 Dissemination The dissemination of a full weights set can be very timeconsuming and difficult to achieve if carried on a manual comparator. To calibrate a decade (for example 1g to 100mg), 10 measurement groups are necessary. 19

21 Content Learning Objectives Principle of a robotic comparator Security Accuracy & Performance Influence of Cornerload Dissemination Productivity 20

22 Productivity Mettler Toledo USA NIST TROEMNER Heusser Neweigh 21

23 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 s if measurement is completed, has started or aborts IMPORT 22

24 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 History Specific Pause 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 23

25 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 24

26 Thank you! Mettler Toledo SPG Metrology Mark Kliebenschädel