What Is Yield Variance?
Yield variance is defined as the difference between the actual amount of finished products
and the expected amount of units produced from a given amount of raw materials used [1].
Yield variance is normally calculated in terms of the cost of the difference as below:
(Actual output in units - Expected output in units) x Standard Cost per unit of raw materials
Wireless Pulse Logger : LR8512
YIELD VARIANCE VALUES
0
> 0
Favourable
< 0
Unfavourable
Produce LESS
nished products
Produce MORE
nished products
Figure 1.0 Yield Variance Values & Interpretation
YIELD VARIANCE
MONITORING WITH
HIOKI WIRELESS LOGGERS
Application Note
Figure 1.0 shows the relationship of yield variance value to the amount of finished products.
In brief, yield variance measures the efficiency of turning inputs into outputs [2]. A negative
yield variance could be due to labor inefficiencies, faulty equipment, improper production
methods, high wastage, inferior materials or use of cheaper mix with a lower yield.
Methods To Track Number Of Produced Units
There are a few methods to track quantities produced [3]
1) Manual count and recording
2) Automatically using direct connection of counter on production equipment
3) Automatically using external add-on attachment to tap to related production
equipment signals (for equipment without built-in counter)
4) Dual mode – Combine manual and automated data collection for flexibility
Hioki LR8512 For Wireless Pulse Output Signal Measurement
The conventional press machine output tracking is by manual count and recording. But
this can be automated with the use of Hioki LR8512. A press machine produces one pulse
signal output with each press. Hioki LR8512 can tap and record the pulse output signals
to represent the output number. The pulse counts displayed are on an instantaneous and
cumulative basis. The automated data collection and recording minimizes human error in
the production output recording.
No. of input
channels
2 channels (common GND)
Measurement
modes
Integrating (cumulative/Instant), Revolution,
Logic (Records an 1/0 for each recording interval)
Supported input
format
Non-voltage “a” contact (always-open contact point),
open collector, or voltage input (DC 0 V to 50 V)
Recording intervals
0.1 to 30 sec, 1 to 60 min, 16 selections
Recording modes
Instantaneous value
Dimensions,
Weight
85W×61H×31D mm (3.35W×2.40H×1.22D in),
95 g (Not including the battery)
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Specications
(Accuracy guaranteed and Post-adjustment accuracy guaranteed for 1 year)
Pulse input
cycle
200 μs or higher when the filter is set to OFF
(must be 100 μs or higher in H period and L period.)
100 ms or higher when the filter is set to ON
(must be 50 ms or higher in H period and L period.)
■
Pulse input
Measurement
Range
Max. Resolution
Measurement Range
No. of revolutions
5000/n [r/s] f.s. 1/n [r/s] 0 to 5000/n [r/s]
* n is the number of pulses, 1 to 1000, per revolution.