The injection molding process used for thermoplastics is easily adopted for TPE/TPV. Among all TPEs, TPU was by far difficult to injection mould because of high viscosity. However the grades are commercially available for injection moulding, lately.
The key TPE properties include:

The processing melt temperature directly correlates with the melting temperature of the TPE polymer. The melt viscosity at the process shear rates used directly correlates with the injection pressure and packing pressure required. The various TPE classes have different viscosity ranges and temperature sensitivity, and these vary from grade to grade. Therefore, the process and mould must be tailored to the specific class of TPE and the grade selected.
A comparison of the relative moulding parameters for the various TPEs is shown in the table below.

The TPVs represent a special case, since the structure does not consist of a single polymer type. TPVs have a cross-linked rubber phase dispersed in a thermoplastic phase. This morphological structure makes them very shear dependent such that the viscosity is quite low at the high shear rates used during injection molding (1,000 to 100,000 sec-1). Then at very low shear (and when static) the viscosity is quite high giving the TPV melt a relatively high stiffness. The grades of TPVs commercially available also vary widely in their injection mouldability. Some are highly tailored to injection moulding and work extremely well. These molding grade TPVs work better in thin and difficult to mould parts. The general purpose grades generally mould well and can be used many TPV applications without resorting to the more expensive moulding grades. But where they are needed, the higher cost is more than offset by the elimination of moulding difficulties.
(Courtsey: Omnexus)