Specification Example: KW6203AF03
||10.4-inch color TFT LCD
|| Maximum display value or less
||2 or 3
This expresses the range of weights that the Checkweigher is able to weigh accurately.
In Anritsu Checkweighers, the maximum weighing range is the maximum weight at which the accuracy can be maintained.
The minimum weighing range depends on the conveyor, balance mechanism, accuracy, scale interval, etc.
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 ±3σ (see Standard deviation). In this case, a smaller value indicates higher accuracy.
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, please note that the maximum speed is not assured for the combination of other related parameters including weighing 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 place a fixed interval feeder.
This is also called the minimum scale and it indicates the minimum pitch of displayed weights.
Limit setting range：
To classify products into 3 groups, "-NG, PASS and +NG", a limit needs to be set to each of the overweight and underweight sides. Limit setting range indicates that the setting range of these limits are between 0 g and the maximum display value.
In general, 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.
Measurement Act (Japan) mandates that when a person sells the commodities specified by Cabinet Order, such person shall measure the specified physical phenomena quantity of such commodities so as not to exceed the measurement error level specified by Cabinet Order. This measurement error is called Quantity Tolerance.
This function automatically switches the weighing 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)
||Reference value+Upper limit
+Tare weight: m
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).
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 ±3s includes 99.73% of the entire frequency distribution.
This value is the sum of the data divided by the number of data items and is expressed by the symbol μ or .
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.
This expresses the ability to distinguish similar weights; the resolution increases as the value gets smaller.
Resolution = Scale interval / Weighing range