The largest manufacturer of load cells in Russia invites you to have an online tour around the factory. This tour will give you an opportunity to learn about every step of the manufacturing process of Tenso-M load cells from delivery of steel from a warehouse and machining a blank for an spring elements on CNC machines to final tests of a finished load cells.
WAREHOUSE OF ROLLED METAL PRODUCTS
Load cells are made from special grades of stainless and structural steel. To ensure good metrological performance of our load cells, we buy metal products of certain quality in large batches from reliable suppliers. The metal products are stored at a closed non-heated and well-ventilated warehouse.
The metal products are cut into blanks at the blank preparation area. The cutting operations are performed on bandsaw machines. There are different types of bandsaw machines and the right one is chosen based on the size of each blank.
Blanks of load cell spring elements are delivered to the all-purpose machines area. Here the blanks have their rough machining. A wide range of machines ensures optimum machining mode and time for different types of spring elements.
Spring elements of our load cells are then machined at the CNC machines area. Tenso-M engineers developed an individual machining program for each nominal size of the cells. The machines ensure a complete cycle of milling and turning operations for spring elements of the load cells. High machining accuracy contributes to good metrological performance of our load cells. Three-shift working schedule of operators ensures maximum utilization of the machines.
MARKING OF LOAD CELLS
Each spring element receives an individual identification number. A dedicated CNC marking machine is used to apply identification numbers to spring elements. These assigned numbers are written to a database that contains all information on each load cell received from each manufacturing step. Later this information may be used for assembling scales.
HEAT TREATMENT OF SPRING ELEMENTS
Heat treatment improves elastic properties of spring elements. Heat treatment is performed in quenching and tempering furnaces of shaft or chamber type. Uniformity and repeatability of furnace treatment modes contribute to good metrological performance of our load cells. Each steel grade has its individual heat treatment mode.
After heat treatment the surface of spring elements of the load cells is cleaned on sandblasting machines. Spring elements made from stainless steel and structural steel are cleaned using different types of sandblasting machines. For sand blasting we use glass beads or corundum.
QUALITY CONTROL OF SPRING ELEMENTS
Our quality control department checks if mechanical dimensions, hardness and roughness meet requirements of engineering documentation for spring elements. For this purpose our engineers use special measuring equipment, including depth gages, hardness testing machines, micrometers, calipers, and etc. Each spring elements is thoroughly inspected.
ULTRASONIC CLEANING LINE
Ultrasonic cleaning line is used to remove oil, emulsion or abrasive materials remaining after machining from the surface of spring elements. After cleaning spring elements are dried and proceed to the next manufacturing step which is assembling of strain- and heat-sensitive circuits.
ASSEMBLING OF STRAIN- AND HEAT-SENSITIVE CIRCUITS OF LOAD CELLS
The strain- and heat-sensitive circuit assembling area is used to glue resistance strain gages, thermistors and termination pads on spring elements. This is done using a special hot curing glue. To protect elements from mechanical damages and atmospheric precipitation, we use special sealants.
Heat treatment is performed in two steps. Each step involves a few temperature layers of certain duration. Gluing is performed using many tools including those for marking, positioning, holding down and assembling.
The wiring area is used to connect strain- and heat-sensitive circuits with a control board and a cable of each load cell. Each load cell also has intermediate quality control here.
ADJUSTING PARAMETERS OF LOAD CELLS
The parameter adjusting area is used to adjust a load cell output based on temperature effect and its degree. Certain types of load cells additionally require adjustment based on effect of eccentricity of load application and nonlinearity. For adjustment we use multimeters, bench-type strain measuring instruments, electronic switches and other equipment. Another important tool of the load cell parameter adjustment is load applying machines, each of them is used for a certain nominal size of load cells. Loading of load cells at a certain constant temperature is performed using special temperature chambers integrated with load applying machines.
SEALING BY LASER WELDING
After adjustment load cells are delivered to the sealing area. Most of our load cells are sealed using laser welding machines. This is the only method to ensure maximum reliable protection of load cells from environment exposure.
First each load cell is tested for leaks using a helium leak detector. This method is widely used in rocket production. If the test is successful, nitrogen is filled into the load cell body to ensure long service life.
Metrological performance of load cells is analyzed using dedicated testing equipment. Each load cell is subject to loads on load applying machines. Availability and diversity of testing equipment are an essential condition for a manufacturer of reliable and accurate load cells.
QUALITY CONTROL DEPARTMENT
Our quality control department receives all finished load cells including information on each load cell. If any load cell fails to meet established requirements, it is sent to the rejects area. Other load cells are marked, packed and sent to the finished product storage. Information of these products is written to a database.
Load cells sent to the rejects area are thoroughly investigated by the most experienced engineers of Tenso-M. Based on results of these investigations we develop recommendations and take measures to prevent these defects from occurring again. Today our rejects ratio is 1 per 10,000 units which is at the level of world leading manufacturers.
FINISHED PRODUCT STORAGE
Load cells are stored on special racks at the finished product area. There is detailed information on available stocks and consumption of products as well as on movement of load cells through the manufacturing process in the company’s database. This information helps to properly plan production processes and respond to customer orders in timely manner.