# The Role of Advanced Manufacturing Technologies in Production Process Performance: A Causal Model
## 2 Literature Review and Hypotheses
[51] claimed that systems based on CNC, CAM, and AMHS make production more flexible and agile. For this reason, considering that companies invest in _Stand-Alone Systems_ to obtain a series of benefits, the following hypothesis is proposed:  
**Hypothesis 4** (H4). : _The Stand-Alone Systems level of implementation has a direct and positive effect on the Production Benefits obtained._  
Moreover, the _Intermediate Systems_ refer to materials transportation and storage of automatic systems, as well as to inspection systems and their implementation in production systems that have been widely reported. For example, [PERSON], et al. [52] mention that AMHS systems help companies in India to reduce the number of accidents due to material handling, increase their industrial safety indexes, and avoid loss of raw material due to inappropriate usage. For instance, [PERSON] and [PERSON] [53] report a simulation implementation to determine the benefits that can be achieved with the usage of AMSH. In the same way, automated inspection systems have evolved and their application in production systems is widely reported. For example, [PERSON], et al. [54] indicated that intelligent manufacturing cannot be conceived without the support of computer vision systems while [PERSON], et al. [55] suggested that vision systems are a fundamental pillar in the Industry 4.0, which support decision systems. According to the previous information, it is observed that an appropriate implemented _Intermediate System_ may offer benefits in the productive system, and the following hypothesis is presented:  
**Hypothesis 5** (H5). : _The Intermediate Systems level of implementation has a direct and positive effect on the Production Benefits obtained._  
Although _Integrated Systems_ are the most expensive and difficult to implement, they are still attractive for managers due to the benefits they offer. For example, [PERSON] and [PERSON] [56] claimed that JIT offers a series of benefits that are directly reflected in the productive system; [PERSON] and [PERSON] [57] performed an analysis of the effects that JIT has when it is implemented, where it indicated that the deliveries on time and fulfillment of complete orders were always obtained. [PERSON], et al. [58] reported a factorial analysis on the different benefits obtained from JIT in the productive systems, and [PERSON] and [PERSON] [59] showed a list of 33 benefits identified in a literature review. In the same way, the benefits from MRP systems have been reported by [PERSON], et al. [60] who had already reported studies justifying the investment in MRP. In addition, [PERSON], et al. [61] pointed out the operative benefits from the tool by having better control and traceability of the requirements; and finally, [PERSON], et al. [62] indicated that JIT and MRP are techniques that must be properly integrated to ensure a better supply chain performance in production systems. Therefore, in the present research, the following hypothesis is proposed:  
**Hypothesis 6** (H6). : _The Integrated Systems level of implementation has a direct and positive effect on Production Benefits in companies._  
Figure 1 portrays graphically the hypotheses that have been previously proposed.