Can We Issue a Show Cause Notice for Negligence Without Union Complications?

We manufacture packaging films (used for food packing). Due to the negligence of our technician, insects got trapped in the product, and our customer sued us. Can we issue a show cause notice to our technician (operator)? The technician/operator is in the staff category as per the appointment issued to them. According to the appointment letter, we can remove them by giving one month's notice pay. If we do this, this fellow can join the union we have for other workmen. If he joins the union, what should we do? Please advise.

Can you prove that your vigil did not have any negligence and it was the fault of the operator only? Can you prove that your administrators were careful enough on paper and can be proven in court? If yes, then you are sure to punish him/her. But if he/she can prove that there was vigil negligence and administrative faults, then you cannot!!

Thank you