ISA95 and MES

ISA95 AND MES

When producing something in a factory, there is often a customer request as the origin for producing something. It is possible that this request comes directly from a customer, or that this request is an internal company request. This request creates a demand which will have to be fulfilled before a certain date, and therefore it has to be planned to be completed before that date. The planned number of products is then produced using the production line, and shipped to the customer. How companies deal with the steps in order acquisition, purchasing, production and shipping, is very different and not always as straightforward as they could be.

The automation pyramid

Because the linking of the business process to the production process requires a large amount of data connections, these must be implemented in a standardised manner. If this is not done in a standardised way, it will become a very cluttered system, and maintenance of the system will become near impossible. The way in which this functionality should be implemented is according to the ISA 95 standard, which applies to the 4th level of the automation pyramid. In the automation pyramid this 4th level connects the business process layer, through an intermediate layer called the Manufacturing Execution System, to the execution layer. MES plays a key role in converting business targets into practical execution plans, and production information into business information.

ERP systems

The Enterprise Resource Planning system ensures that all company resources are planned where they are needed. This means the employees, materials, machines, offices, money and all other resources, are planned based on time and task. The production environment is therefore also planned, and the associated tasks are assigned to it to ensure that the orders that need to be fulfilled, which are booked in the ERP system, can be delivered on time.

Because this information needs to be communicate to the production department, this information is usually given to them as a list so that the orders can be executed. These are then handed to the production department in a departmental meeting. But an error in quantities or a small miscommunication is quickly made. To prevent these small mistakes, that have a big impact,  we should be making the system digital so that this information is communicated directly to the production systems from the ERP.

The MES System

The MES distinguishes a number of data flows and functionalities. The functions that we can define within an MES are laid down in the ISA 95 standard, and contain not only production information, but also information that can affect production, or that should be taken into account for production. The ISA 95 model has a number of functionality modules that can be linked to business or production functions in order to set up a total plan for communicating between the business and production processes. We can classify these functions into a number of function groups.

Production functions within an MES

Because the production data stream is very important in this standard, these functions have been given numbers 1 to 3. These 3 functions are the following:

• Order Processing
• Production Scheduling
• Production Control

These functions describe (Order Processing) retrieving the orders from an ERP system, converting them into a production order, and creating the production order in the production system. Once that is done, the production orders must be included in the schedule (2. Production scheduling), the rules of LEAN can be used to automatically use a method for scheduling the production runs. After production has started, these production orders are managed by the operators (3. Production control), and the data is read from the process automation system by the MES. Because the MES reads this data, all data from the production runs can be tracked in the MES, reported on by the MES and other MES functions can use this data.

Material Management and Product inventory control

Because there often has to be a check at the start of production, whether there are still enough source materials available, or because information about input materials or output products is required (Product inventory control), material information is stored. An MES can ensure that this information is given to the ERP system. When the ERP system knows the usage of raw materials in a production run, it is possible determine how much product we can get from a production run. The ERP system can no monitor the next delivery date for raw material to ensure the production schedule for the quantity of sold product can be met.

Material management also ensures that the MES can plan when a production run can take place. By means of the order data from the ERP system, the MES can determine when a material arrives and when the best time is to start a production order.

Procurement and Financial control

Because we have modules that depend on financial data, the MES has a number of financial modules. These modules are:

• Procurement
• Product cost accounting
• Product shipping admin

By interfacing how much material, energy and hours of employees have been used in the products of a product, the ERP can determine how much one product costs. With this, the full cost of a product can be tracked over the a longer period, and the ERP system can monitor whether the cost of the product is going up or down.

Quality management

Products and materials must meet certain quality requirements before and after production. This data can be passed on to the ERP or laboratory system where the quality requirements have been laid down. If the laboratory information system detects any quality issues, it can tell the MES to mark that product for removal. The MES will then remove the product from the product inventory, and send the data to the ERP for business reporting.

Maintenance management

During daily maintenance, often a system needs to be switched of temporarily. The MES can process this in the production planning via the maintenance module. This link can enable or disable production units from the scheduling algorithm, so that automated choices can be made in production and planning. The MES system can also track the wear of equipment, by processing the data from power meters or from the process automation system data. This data can be monitored by the MES, and the MES can set a maintenance alarm when the equipment shows signs of wear.