Counting scales can offer incredible benefits to any stock taking or annual inventory counting tasks.Counting scales can enhance production and human error in counting is virtually eliminated.
Parts counting scales are normally used in warehouses , factories , hardware stores , paper plants , pharmaceuticals , plastics , electronic and automotive industries.
A typical counting scale will have three displays i.e. weight , piece weight and total.
The internal resolution of a counting scale is very important . The higher the internal resolution , the higher the counting accuracy for a given sample size.
Counting scales are very similar to other scales in terms of weighing, but the counting scale has two additional functions, by performing operations in division and multiplication based on the internal resolution.
1. What is internal resolution?
The internal resolution of a counting scale is the number of divisions into which it divides the total capacity of the scale.
Example: A 15 kg counting scale with 1 million count resolution divides up the 15 into 1,000,000 parts. This means each internal resolution is translated to 50/1,000,000 or 0.00005 kg . All of the weights are calculated on this basis. For example, if some parts were placed on the counting scale, and the internal calculation was 210 internal counts, the weight to be displayed would be 210 times 0.00005 kg = 0.01050 kg. Since the weight display might only be five digits, then the weight display would be 0.0005 kg. This is the external resolution. (rounded off).
With a normal counting scale , the operator can key in the sample quantity—for example, ten pieces through the keypad on the scale. The scale still “knows” how many internal counts are being used (210) and now divides that number by 10 to get the number of internal counts per piece (210/10 = 21).
Next the scale needs to convert the piece weight into kilograms or grams, by simply multiplying the weight per count times the number of counts (0.00005 times 21) = 0.00105. This is displayed in the Unit or Piece Weight window. At this point the scale needs only watch for a change in the weight and redo the calculation in reverse, using the number of internal resolutions per piece as the divisor. For example, more pieces are placed on the scale and the number of internal resolutions is now 187091. So 187091 / 21 = 8909.09 which is rounded to 8909 pieces.
2. What is external resolution ?
This is what is displayed in the weight window of a scale. It is also called display resolution and is calculated by taking the capacity of the scale and dividing by the resolution. In most load cell based counting scales, the external resolution will be one part in 10,000 also expressed as 1/10,000.The displayed resolution is not as important in a counting scale since the calculations are all made using internal resolution. The only time the external resolution comes into play is when a tare weight is being manually or digitally introduced.
3. What size sample should be used ?
The minimum sample recommended is 10 pieces. However, here are some considerations:Is a 10 piece sample sufficient weight on the platform? The sample should be at minimum 0.1 percent of the total capacity.How uniform are the parts being weighed ?
A larger sample size provides sufficient data to determine the most accurate unit weight. Sampling for example a 100 pieces is recommended to achieve the best accuracy. A larger sample of 10 groups of 10 can be counted out by hand, and placed on the scale as a 100 piece sample.
Below is a typical counting scale with internal resolution of 1:600 000
Model shown Adam CBC 16 kg accuracy 0,5 gr.
Three Large backlit LCD displays ( weight/ unit weight and count / total )
Simple user-friendly operation
Dust cover to protect from accidental spills
Full colour coded keypad with numeric entry
Large stainless steel pan
Non-slip adjustable feet
Full range tare facility
For more on counting scales and internal resolution below is a link
Watch this video overview of a typical counting scale.
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