The answer to the question depends entirely on the HR policies and management style of the company. If an employee has caused problems or inconveniences in the plant's operations, the Operations department will communicate this to the HR department. I'm pretty sure HR will not be aware of the operations part, so an investigation has to be conducted through the HR department. The guilty party must be given a chance to speak. Upon conclusion from the external agency (HR), the employee shall be issued a warning letter if found guilty.
If the employee has behavioral problems or requires disciplinary action, it can be directly handled through the HR department, provided that the HR department also informs the Operations department. This is because HR manages appraisals.
Regards,
Yashwanth R