Innovation Electronic Co.,Ltd
Use our Machine To Make Your Weighing and Packing Line Easier, Faster and More Cost Saving!
From machining the steel workpiece to packaging and shipping, through gluing the strain gauges, wiring, calibration and testing...here are all the steps in the construction process that turns a simple steel cylinder into the most important component of a weighing system.
The construction of the load cell starts in the mechanical workshop where the Aluminum bars arrive to be transformed.
Aluminum, due to its elasticity and hardness, is a particularly suitable material for load cells.
When combined with the proper strain gauges, it has a very small error on the hysteresis cycle.
This characteristic allows it to remain flexible even for very high forces: it deforms under a load and then returns to its initial condition when the load is no longer acting.
All bars are certified with an ultrasonic machine to rule out any imperfections in the steel. Then each bar is marked with its diameter and casting number so that the batch is easily traceable.
The bar is cut into cylinders, which are then checked one by one to make sure that there are no "cracks".
Cracks are often hairline cracks invisible to the human eye and may cause future problems when manufacturing the load cell or operating it.
Once the checks are passed, the cylinder is machined in 3 stages: two on the lathe and one on the milling machine.
The load cell mechanics are ready for moving on to the next stage of manufacture.
Once the blank body of the load cell has been received by the workshop, the first mechanical test is carried out.
The operator, using a periodically certified gauge, checks that the dimensions are within the tolerances specified on the design drawing.
To remove all traces of impurities, the part is then washed a first time with a degreasing emulsion at a temperature of 50° for 40 minutes.
This is only the first wash the load cell will undergo, as a matter of fact it will be cleaned at least another 4 times.
Finally, all the clean parts are dried by hand one by one.
The heat treatment of aging serves to eliminate and ease the tensions in the material and to bring the load cell to the desired hardness, improving its elasticity.
Aging leads to the core of load cell production.
4. Polishing and sandblasting
After heat treatment, the load cell is polished and sandblasted.
The load cell is transported to the laboratory, where it is subjected to two checks: the dimensional and flatness checks.
After polishing and the mechanical checks, the hardness of the load cell is checked.
Approximately 10% of the pieces are checked at random, which is sufficient to ensure that the whole batch meets the required parameters.
7. Laser tracing and marking
Both tracing and marking are done with a laser marker that can engrave any material, for an extremely clean and precise result.
8. Ultrasonic cleaning
Once all the mechanical checks have been completed, the load cell is washed again.
This time an industrial ultrasonic washing machine is used to make sure it gets completely degreased.
9. What is a strain gauge and how does it work?
The strain gauge is a small grid consisting of constantan wires (a binary alloy of copper and nickel) and is the sensitive measuring component of the load cell.
10. Cleaning with conditioner and neutralizer
The load cell now reaches the most delicate department. It is here where the strain gauges are selected, positioned and glued expertly by skilled and specialized technicians.
Everything in this department is kept under the utmost control: the temperature is always between 20°C and 24°C, the level of humidity is kept constant and there is no dust whatsoever.
Everything is carefully monitored, nothing must affect the strain gauge and its isolation.
However, the load cell must be cleaned once again before gluing.
This is the most important step in load cell production.
It is precisely the accuracy of the gluing, performed by hand by extremely skilled operators, that esures optimum load cell perfomance in terms of repeatability, linearity and combined error.
12. Wiring
After gluing the strain gauges, the load cell wiring is made.
13. Calibration
The calibration test is used to measure the load cell response at 10 points up and 10 points down and the measured values are expressed in mV/V.
The response of a load cell must be directly proportional, i.e. linear, to the applied load (from 0 to its maximum capacity).
14. Temperature test
The load cell is placed in a climatic chamber, where the temperature test for the 0 thermal drift compensation takes place.
1 - Resinating the cable
2 - Resinating the load cell slot
Once the resin has dried, the operator places the cover that will protect the slot ans fits it into the recess of the load cell.
The cover is designed specifically for each type of load cell and is made to measure with an elastic material so as not to affect the performance of the load cell in any way in terms of combined error, repeatability and linearity.
17. Testing the load cell and printing the certificate
18. Packaging and shipping
Contact Person: Miss. TINA LIU
Tel: +8618758163948
Fax: 86-571-8838-5175