Often the question industrial machine manufacturers are faced with is, “Should I make or buy the HMI?”.
HMIs (Human-Machine Interfaces) come in many formats and vary in complexity, making it more difficult when it comes to make or buy decisions. An HMI can be a simple set of control buttons on a machine, interface software, a display terminal, or an advanced touchscreen capable of data archiving and remote real-time data delivery.
One route that some manufacturers take – if they do decide to implement their own HMI solution – is the HMI software development path. There are software programs that allow you to develop HMI software, and that also come with templates for standard factory functionality such as monitoring a valve or pump. However, as the complexity of a certain manufacturing process increases, this is not always a viable option.
Of course there will always remain the less glamorous activity of developing the hardware. Given this new product will most likely be used for over 5 years, in continuous use, the design and development of the hardware is no banal process, requiring many years of real life experience. As Steve Jobs once said regarding the engineering of hardware, “there are just some things that the law of physics impedes”.
In this article, we will review some of the main factors to consider when it comes to make or buy decisions for HMI development. This list is not intended to be in order of importance.
8 Questions to ask when deciding to make or buy the HMI
1. Which processes and operations does the HMI need to control in the factory?
The first step involved in deciding whether to make or buy the HMI, is reviewing the factory processes, assembly lines and operations the HMI will have to monitor or control.
For example, the processing of milk at a typical plant initially involves pasteurization where the milk is heated and cooled to remove pathogens.
The next treatment phase is generally homogenization, where the milk is put through an atomizer to ensure that the fat particles are distributed evenly throughout the milk. The milk is then exposed to other processing, such as the reduction of fat content by micro-filtration, or increasing the storage shelf life by ultra-high temperature treatment.
The entire process is automated and each treatment phase could, depending on the plant, have an HMI connected to a PLC (programmable logic controller) for monitoring and ensuring that the milk meets quality standards.
In this scenario, since the automation in milk plants is fairly sophisticated but well documented and understood, it would be more expedient for the factory owner to invest in purchasing the HMI, as part of a SCADA (supervisory control and data acquisition) system.
Alternatively, if the factory was producing their own brand of milk and exposing this milk to a specialized process that adds set amounts of additional protein and calcium, they could integrate their own HMI into this particular stage.
Consequently, it is advisable that the factory owner should evaluate existing processes in great detail. For example, the equipment the HMI needs to connect to, as well as specialized needs; then this information can be utilized to make a decision.
2. Which machines and parameters need to be monitored in the factory?
Manufacturers can review the different parameters associated with a machine, using an HMI. The standard parameters that an HMI associated with a specific machine usually measures are variables such as temperature, outputs, machine counts and pressure.
Additionally, the typical HMI in use at water treatment plants for example, can display which valves are still open or pumps that are still running. These are all very simple standard measures, and a factory owner could readily implement an in-house HMI solution for these types of measurements on less complicated machinery.
Many factories do have more complicated machinery and more complex parameters that need to be measured. For example, machinery involved in the assembly of motor vehicles sorts parts based on geometry and other features, so a more sophisticated HMI would likely need to be purchased.
3. How complex does the HMI need to be?
An automation engineer could create a simple HMI for a water storage plant for example, which displays the water levels in a certain tank. This would be a fairly simple HMI software application to develop and code.
However, many manufacturing processes are made up of different stages. These stages could be mechanical or chemical. Therefore, if the HMI has to monitor and deliver data on different stages, the algorithms needed would be more complex. For example, the pelleting of biomass involves filtration, drying to remove moisture content, and the addition of binders or lubricants, so the HMI controlling this process would need to be more advanced to suit the process.
It is important to remember that the complexity of the HMI is directly correlated to the process it needs to monitor and control. This is an important factor when considering to make or buy the HMI.
4. Do you have the time for design, development and implementation of the HMI?
The time frame for the entire development lifecycle of the HMI, if designed in-house, has to be taken into account when decided to make or buy the HMI. Ideally, the HMI has to be user-friendly and intuitive for the front-end factory staff to operate. There needs to be time for development, testing and thorough integration into existing factory architecture and platforms.
This means that a considerable amount of time may have to be set aside to accommodate the lifecycle, which could affect the company’s bottom line.
Often these in house projects much attention is given to the development stage with little to the implementation stage. Here outsourcing some technical requirements frees up time and resources to ensure adequate take up.
5. Is it feasible to develop an HMI concurrently with the pressures of product revisions and machine upgrades?
Another factor, which will have an impact on the decision to make or buy the HMI, is the market and the unique pressures it puts on the factory.
Manufacturers frequently have to develop products and upgrade existing machinery in order to deal with competition and implement sophisticated production lines. If the HMI is developed internally, the HMI would also have to be upgraded to deal with these challenges which may not be concurrently possible.
It’s important when considering the feasibility of developing the HMI in-house, if it will be compatible with new machinery going forward.
6. Is it possible to incorporate outside technology within the existing internal development teams?
If a manufacturer has decided to develop their own HMI, then it is advisable that they also incorporate outside technology and experts into the existing internal development teams in order to speed up the product lifecycle and to leverage external skills.
This combination of outside technical assistance with the existing internal workforce can produce very fast to market results. Certainly at the embedded level, this can be a very powerful project set up.
7. What is the available budget?
In terms of a simple HMI software application that monitors tank levels for example, this would be a fairly inexpensive undertaking. In a situation where a factory owner required an HMI to provide historical data information on multiple machines, real-time data, tracking and remote control, the budget would increase significantly.
Therefore, the factory should ensure that they have the financial resources available if they intend to undertake the development of a more complex, embedded HMI.
8. What are the end goals – a simple prototype for a research project, or a fully loaded, working and controlled version of the HMI?
The last point that has to be evaluated is the end goal. For a simple HMI prototype that is mainly for demonstration purposes – the manufacturer could look at designing their own HMI if they have the in-house skills. Alternatively, if the manufacturer requires an HMI that is a fully loaded, working and controlled version, that is interoperable, can connect to multiple machines and be upgraded easily; then the decision to purchase should be seriously considered.
Final thoughts
The choice to make or buy an HMI depends on a number of factors. It is advisable for manufacturers, should they have an extremely complex process to control, to purchase an HMI. However, they are not prohibited from implementing their own solution provided they are aware of all the advantages and disadvantages associated with this option.
