The cone of the cone penetration tester is the core measuring component, and its cleanliness and integrity directly affect the accuracy of the cone penetration results (such as residual samples changing the actual weight of the cone and affecting the initial state of the contact sample at the Jian end), so it is necessary to strictly follow the cleaning and maintenance specifications. The following are specific precautions:

1、 Cone cleaning: "Timely, gentle, and residue free"

Cone cleaning requiresImmediately after each testThe cleaning methods for different types of samples (such as lubricating grease, asphalt, paraffin, etc.) may vary slightly, but the core principles are the same:

1. Selection of cleaning tools: Avoid damaging the cone

toolSoft tools (such as lint free cotton, dust-free cloth, soft bristle brush), specialized solvents (compatible with the sample and not corrosive to the cone material);

Disabled toolsHard tools (such as steel wire balls, blades, sandpaper), corrosive solvents (such as strong acids, strong alkalis), avoid scratching the cone surface, wearing the end, or damaging the cone metal coating (usually chrome plated to ensure smoothness and rust resistance).

2. Classification based cleaning process (based on common samples)

2、 Cone maintenance: "Regular inspection, proper storage, and timely replacement"

1. Daily maintenance (after each cleaning/once a week)

rust prevention treatmentIf the instrument is not used for a long time (more than 1 week), after cleaning and drying, a thin layer of anti rust oil can be applied to the cone surface (it needs to be wiped clean with solvent to avoid affecting the test);

Inspection of connection partsCheck whether the connection between the cone and the connecting rod is loose (such as whether the threaded connection is firm). If it is loose, gently tighten it (do not apply too much force to prevent thread damage);

avoid collisionWhen taking and placing the cone, it should be handled gently. It is forbidden to place the cone randomly on the desktop (to avoid deformation caused by hitting hard objects at the end). It should be placed on a dedicated cone bracket (the bracket should be flat and free of impurities).

2. Regular inspection (once a month/before calibration)

Size and weight inspection：

Weigh the total mass of the cone (including the connecting rod, usually 100g or 200g) using an electronic balance with an accuracy of ≥ 0.01g. If the mass deviation exceeds ± 0.05g (within the allowable range of the standard), stop using and replace it;

Use an optical microscope (magnification ≥ 20x) to check the angle of the jian end (as required by GB/T 269, 60 °± 0.1 °). If there is an angle deviation or if there is a notch or wear on the jian end, the cone needs to be replaced;

Surface condition inspectionCheck if there are scratches or peeling of the coating on the conical surface (peeling of the coating can cause the sample to adhere and rust easily). If the damage affects the measurement, it should be replaced in a timely manner.

3. Replacement and scrapping: Clarify "when to replace"

When the cone experiences the following situations,Must be scrapped and replaced with a new cone(Non repairable to avoid accuracy deviation caused by maintenance):

Severe wear, passivation, or gaps on the Jian end (unable to guarantee the accuracy of cone penetration depth);

The cone surface has deep scratches and a large area of coating peeling off (which is prone to residual samples and may corrode the cone body);

Quality deviation exceeding ± 0.05g (or judged as "unqualified" in the calibration report);

The connecting thread is damaged (unable to firmly connect the connecting rod, may shake when falling).

4. Storage requirements: moisture-proof, dust-proof, and pollution proof

Storage environmentPut the spare cone or cleaned cone into a dry, sealed container (such as a plastic box with desiccant) to avoid rusting in a humid environment;

Isolation storageDo not place it together with oil stains, corrosive reagents, etc. to prevent contamination of the cone surface;

Identification ManagementClearly label cones of different specifications (such as 100g, 200g) to avoid mixing (cones of different weights correspond to different testing standards, and mixing can directly lead to incorrect results).

3、 Common Misconceptions to Avoid

If there are few samples, there is no need to clean themEven if the cone surface appears to have no obvious sample after a single test, it still needs to be cleaned according to the process (trace residues will accumulate, which will affect weight and measurement accuracy in the long run);

Clean quickly with strong solventsIf acetone is used to directly clean grease samples, although the cleaning is fast, it may corrode the cone coating. It is recommended to prioritize using a special mild solvent;

If the calibration is qualified, there is no need for maintenanceIf frequently used during the calibration cycle, it is still necessary to regularly check the status of the cone (such as checking the Jian end every week) to avoid result deviation caused by accidental damage during use.

Through standardized cleaning and maintenance, the service life of the cone can be extended while ensuring consistent initial conditions for each test, reducing systematic errors and poor repeatability in cone penetration results from the source.