Absence of Which in Non-restrictive clauses

Is it necessary to place the which after the comma in the first two sentences (Non-restrictive clauses)?

1. The Nb thin films were deposited through HiPIMS with an industrial tool coating machine produced by CemeCon 8.0, displayed in Figure 8.

2. The space between the two electrodes is filled with a process gas, typically an inert gas such as argon.

or

3. The Nb thin films were deposited through HiPIMS with an industrial tool coating machine produced by CemeCon 8.0, which is displayed in Figure 8.

4. The space between the two electrodes is filled with a process gas, which is typically an inert gas such as argon.