To avoid damaging plastic and rubber workpieces during the shot blasting process, the following measures can be taken:

1. Choose an appropriate cleaning method: Consider using alternative cleaning methods suitable for plastic and rubber, such as chemical cleaning, spraying, or manual cleaning. These methods are gentler on the workpiece surfaces and reduce the risk of damage to plastic and rubber.

2. Limit shot blasting machine parameters: If shot blasting is necessary, restrict the parameters of the shot blasting machine to reduce the impact force on plastic and rubber workpieces. This can include reducing the shot blasting velocity, using less abrasive material hardness, or employing smaller shot sizes.

3. Protect the workpiece surfaces: Before placing plastic and rubber workpieces into the shot blasting machine, take appropriate protective measures to prevent direct contact with the shot stream. Special protective covers, coatings, or overlays can be used to safeguard the workpiece surfaces and minimize damage caused by shot blasting.

4. Conduct sample testing: It is crucial to perform sample testing before actual operation. Select a small piece of plastic or rubber workpiece as a sample and conduct shot blasting cleaning tests to evaluate the cleaning effectiveness and potential damage. Adjust the parameters based on the test results to minimize harm during actual operation.

5. Seek professional consultation: If needed, consult professionals or relevant manufacturers to obtain specific advice and guidance for cleaning plastic and rubber workpieces. They can provide recommendations based on experience and expertise to help you choose appropriate cleaning methods and parameter settings.

Please note that the cleaning process for plastic and rubber workpieces may require special considerations and customized solutions. Therefore, in practical operations, it is recommended to take appropriate preventive measures and follow relevant safety guidelines based on the specific workpiece material and cleaning requirements.