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Glossary

Checkweighers

Weight range:
This expresses the range of weights that the Checkweigher can weigh accurately. In Anritsu Checkweighers, the maximum weight range is the maximum weight at which the accuracy can be maintained. The minimum weight range depends on the conveyor, balance mechanism, accuracy, scale interval, etc.

Accuracy:
In the case of a static balance, this expresses the accuracy (difference between true weight and displayed weight) as balance accuracy rank. In Checkweighers, since the main purpose is to automatically select products according to whether or not they meet a target weight, the balance accuracy is expressed as the accuracy using ±3s (see Standard deviation).
In this case, a smaller value indicates a higher sensitivity.

Maximum speed:
This expresses the maximum number of products that can be Checkweighed in 1 minute. Although maximum speed is given in the catalog, the actual speed changes with the product size and required accuracy. In other words, take care to note that the maximum speed is not assured for the combination of other related parameters including weight range, accuracy, product size, etc.
In addition, when the performance of an upstream packer is 50 products/minute, the theoretical maximum performance for the Checkweigher should be 50 products/minute too, but if there is randomness in the feeding of the products between the upstream packer and checkweigher, the interval between products may vary and the momentary maximum performance may exceed 50 products/minute when the products are closely spaced. In this case, the Checkweigher speed may require some margin or it may be necessary to attach a fixed interval feeder.

Indication range:
This is the maximum weight value (measured weight) that can be displayed. Usually, it is 1.1 times the weight range (excluding SV series). In the SV series Checkweighers, it is the range regulated by the international OIML standards.

Scale interval:
This is also called the minimum scale and it indicates the minimum digit of displayed weights.

Limit range:
When products are selected into three ranks of -NG, PASS and +NG, the underweight and overweight limits must be set. The setting range for these limits is expressed as 0 g to Indication range.

Classification:
Generally, the Anritsu catalog describes rejectors as having two or three ways; the two ways are -NG and PASS while the three ways are -NG, PASS and +NG.

Multi-range:
This function automatically switches the weight range and scale interval to match the weight of the product to increase the accuracy. For example, when the weight is 2500g and scale interval is 0.1g, the resolution is 1/25000 but when the weight is 250g, the accuracy drops to 1/2500. By using the multi-range function, when the weight is 250g and the scale interval is 0.02g , the resolution can be maintained at 1/12500.

[As explained in the SV-series Checkweigher Operation manual (see table below)] by using the multi-range, the minimum measured weight and scale interval are selected automatically within the upper limit (reference value + upper limit + tare weight)
Checkweigher Reference value+Upper limit +Tare weight m Weight range (g) Scale interbal (g) KW6200 Type 0 < m ≤ 300 300 0.01 300 < m ≤ 600 600 0.02 KW6400 Type 0 < m ≤ 600 600 0.02 600 < m ≤ 1200 1200 0.05 1200 < m ≤ 2000 2000 0.05 2000 < m ≤ 3000 3000 0.1

Batch:
This is the term for one set of data that is subjected to statistical processing. For example, when using the Checkweigher statistical records, subtotals are saved for the count set at B (Batch count).

Auto-sensitivity calibration:
This function performs auto-sensitivity calibration using the balance internal calibration weights. It eliminates troublesome manual sensitivity calibration and operation errors.

Standard deviation (σ or s):
The weight of products is described by a normal distribution that can be expressed by the standard deviation and mean value. The standard deviation is a measure of the degree of randomness - smaller values of sigma indicate a smaller degree of randomness (or dispersion). A range of ±3σ includes 99.73% of the entire frequency distribution.

Mean value:
This value is the sum of the data divided by the number of data items and is expressed by the symbol μ or .

Randomness (R):
The randomness is expressed as the maximum value minus the minimum value.

Fixed interval feeder:
This feeder feeds random products on the conveyor at a fixed interval.

Resolution:
This expresses the ability to distinguish similar weights; the resolution increases as the value gets smaller.
Resolution = Scale interval ÷ Weight range