A method for measuring the cross-linking degree of a component of elastomeric material

A method for controlling a quality of a component made of at least partially electrically-conductive elastomeric material, configured for being installed on-board of a motor-vehicle, said method comprising the following steps:

• performing a hot-forming process for obtaining a component made of at least partially electrically-conductive elastomeric material said component being in its final shape for being installed on-board of a motor-vehicle,
• performing a preliminary calibration step comprising:
• providing a plurality of samples made of a same material of said component, wherein said samples are obtained with different degrees of cross-linking following respective hot-forming processes conducted for different periods of time;
• leaving said samples in a resting condition at room temperature;
• providing a measuring device comprising an electrical circuit, in which a voltage generator arranged in series with metal contacts configured to selectively receive a sample, and an ammeter;
• positioning a sample between said metal contacts, that said sample is not subject to bending,
• providing a predetermined voltage value by means of said voltage generator;
• detecting a corresponding current value by means of said ammeter:
• leaving the sample (8) again in a resting configuration at room temperature;
• repeating the aforesaid steps of positioning the sample between the metal contacts providing a second voltage value and detecting the corresponding current value, in which the second voltage value generated by said voltage generator is different with respect to the previously applied voltage value;
• repeating the aforementioned steps for each sample, so as to obtain a calibration map that associates a given degree of cross-linking of the material constituting said component with each determined value of electrical conductivity;
• performing a step of measuring the electrical conductivity of said component in its final shape configured for being installed on-board of a motor-vehicle, to compare said conductivity value with a predetermined threshold value obtained from said calibration map and obtaining information on the quality of the component based on the aforesaid comparison;
• in such a way that, after obtaining information on the quality of the component based on the aforesaid comparison, if the quality of the component is lower than a minimum acceptable value, proceeding to scrap the component obtained with a hot forming process carried out with incorrect conditions, thus avoiding installing of a defected component on-board a motor vehicle.

A quality control apparatus for controlling the quality of a component made of at least partially electrically-conductive elastomeric material, obtained by a hot-forming process and being in its final shape configured for being installed on-board of a motor-vehicle,

• said quality control apparatus being configured for evaluating the cross-linking degree of the component,
• said quality control apparatus comprising:
• an electrical circuit configured to measure the electrical conductivity of the component, and
• an electronic controller associated with a memory containing a calibration map that associates a given degree of cross-linking of the material constituting said component with each determined value of electrical conductivity,
• said electronic controller being programmed to receive information on the electrical conductivity value of the component from said electronic circuit, to compare said conductivity value with a predetermined threshold value obtained by said calibration map and to provide information on the quality of the component on the basis of the aforesaid comparison.