Chapter 6

Specification Preparation

Abstract

This chapter describes how a specification conveys the needs of the customer while providing a common basis for comparison of supplier proposals. To this end, we discuss the main items covered by the specification, including the requirements for the automation solution (e.g. parts to be processed and production rates) and the customer requirements for the execution of the project (e.g. project management expectations and project timing). We also address the key issue of buy-off criteria, together with the testing stages that should be performed within a project.

Keywords

User requirements specification

Factory acceptance tests

Site acceptance tests

Turn-key

Buy-off

Golden part

The purpose of a specification is twofold. First, the specification conveys to potential vendors the requirements for the automation solution. In other words, it presents information such as the production rates, parts to be handled, and any standards to be applied. Second, the specification defines how the project is to be handled. This includes the time scale, any reporting requirements, and most importantly, the testing that will define if the system has met the requirements of the customer. As a result, the specification is often referred to as the user requirements specification (URS).

Most automation systems are purchased without a detailed specification. Many customers rely on verbal conversations with potential vendors to define their wishes. The vendor then provides a quotation that may include some of these requirements, but the quotation is often phrased in a way that suits the vendor. Some requirements may have been misinterpreted by the vendor, or even missed completely. There are two problems with this approach.

First, it is very difficult for the customer to compare quotations from different vendors. They may nominally be quoting to the same objective, but there may be significant differences between the quotations that are not apparent on paper. Second, the lack of a real specification is only acceptable until the system fails to meet the customer requirements or until problems are encountered in the execution of the project. Although it is better for all projects to be executed as anticipated, with the results always meeting the expectations of the customer, this outcome is less likely if the vendor is not using a clearly defined specification. Without the specification, something is more likely to go wrong. In many ways this is the fault of the customer: ‘If you don’t tell them what you want, then don’t be surprised if you don’t get it’. The development of a detailed specification can be time consuming, but it is very worthwhile, both in terms of vendor selection and project execution. There are many ways to convey this information, and the level of detail can vary significantly. The size and scope of the automation system can also impact the size of the specification. However, there are a number of specific elements that should be included, and these are reviewed in the following sections.

6.1 Functional Elements of a Specification

As mentioned above, the first objective of the specification is to convey to potential vendors the requirements for the automation project. To achieve this goal, a number of key issues need to be addressed.

6.1.1 Overview

The first step is to provide an outline of the current operation and process. The intent is to clarify the context for the automation project. This outline should include the products being addressed, the operations performed, and the manual input required. Any significant issues with the current operation should be highlighted, particularly if the automation system is intended to offer a solution to these issues.

6.1.2 Automation Concept

Based on the overview, the specification then explains the purpose of the automation system. This part introduces the specific requirements to be achieved by the automation, although these will be specified in more detail later. At this stage, the specification should highlight the key stages in the automation system, including the part input and output and how this would integrate with the existing operations. Any initial thoughts as to potential concepts and solutions should be identified to provide guidance to the potential vendors. Although the customer may not have developed the final solution and may also be open to alternative approaches, the specification should offer some guidance because this assists the vendors in understanding the objectives of the customer and the level of automation they will be considering. Providing this information also helps vendors determine if the project is suitable for their expertise. Providing clear direction reduces the time spent by the vendors in the development of their proposals. It also reduces the time required by the customer in both providing the assistance required by the vendors to understand the requirements and the assessment of the proposals when they arrive.

6.1.3 Requirements

This section of the specification is critical because it defines the main parameters and operating requirements for the automation system. First, details of the products are provided. These details include dimensions, weights, and possibly drawings for each of the parts and any assemblies to be considered. The specification must state any tolerances on these dimensions, as well as any tolerances on the presentation of the input parts, if relevant. These tolerances must be the actual tolerances that the automation must handle rather than anything detailed on drawings. Therefore, this section can provide the major challenge. However, it is key to the success of the project. If the system is developed to accommodate a range of tolerances but, in reality, it is presented with parts outside of those tolerances, it will not operate successfully.

The output requirements must also be specified. In particular, the document should address whether the output is to be presented in a specific way (e.g. stacked on a pallet with a particular stacking pattern). The interface of this output to the following operations may also need to be stated, particularly if manual intervention is required at this stage.

The required throughput, or cycle time, for the system must be defined, as well as the availability required of the system, which is the percentage of time the system is expected to be operational and available to work. The actual production output required is the combination of the throughput and availability. It is not sensible to aim for a cycle time that achieves the required production output at 100% availability because this does not allow for any downtime due to maintenance, material replenishment, lack of operators or any other factor that can impact on the availability of the system.

If the system is to handle more than one product, or more than one product size, the batch sizes should be discussed. Additionally, the specification should cover the requirement for the product changeover, which could be automatic or require manual input. The need for any checking, to ensure the correct product is being processed, should also be included. In addition, it may be necessary to address any implications for the run-out to allow the system to be emptied of a product. The document should also detail any anticipated need for manual intervention and how this is to be achieved.

The customer should include some description of the controls and particularly the human machine interfaces (HMI). This may not be the detail of exactly what equipment is to be provided but rather the functionality that is expected. Such requirements include operator selectable functions, such as start, stop and access to system requests. The customer can also help the process by specifying the types of errors to be logged and how they will be logged (e.g. over what period and the level of fault diagnosis that is expected). If possible, any overall requirement for error recovery should be described. Also, the specification should include any requirement for production management information, such as parts per hour, downtime and cause. If any of this information is to be provided to an external system, this requirement must also be defined. The types and numbers of displays may be specified to provide a guide to the vendors.

Finally, the document should include any specific requirements relating to guarding, safety, and environmental issues. For example, the specification should address the construction of the guarding, such as solid panels, weld mesh or plastic, and also any preferences as to the guarding of operator access stations, such as roller shutter doors or light guards. If there are any requirements for dust or fume extraction, these also need to be included.

6.2 Scope of Supply

The scope of supply is also important. The previous elements of the specification basically define what is required from the automation solution, but this section details exactly what is required of the potential vendors. For example, scope of supply specifications may include the design, manufacture, assembly, testing, delivery, installation, and commissioning, as well as any training and post-commissioning support. It is also important to define the acceptance criteria. Most of the above can be covered by the term “turn-key”, but that is open to interpretation, and it is better to specific exactly what is expected. This section of the specification therefore defines the expectations of the customer for each stage of the project.

6.2.1 Free Issue

If any equipment is to be free-issued by the customer, that equipment must be detailed, including the specification and supplier details. This free-issue equipment may be existing machines or new machines that the customer intends to purchase as part of the project. If these are to be integrated within the automation system, the customer needs to define the specification of these machines and how they are to be interfaced with the automation system. This interface information includes communication as well as mechanical issues, such as access for unloading and reloading. If the machines are to be delivered to the vendor during the project, the availability and timing should be detailed and also the delivery and return should be covered. If any parts are to be provided during the project, as might happen for testing, the type and availability of these and the timing should be detailed.

6.2.2 Safety

It is important to identify the safety requirements and, in particular, any customer specific requirements that should be covered. If there are any specific items that are not to be included in the scope of the vendor, such as fume extraction equipment, the specification should clarify the interface between that to be provided by the vendor and that to be provided by the customer.

6.2.3 Services

The vendor needs to be made aware of the provision of services to the automation system. In particular, the power and air, including the location and number of service drops, which are available for the system. It is also important to state who will be responsible for the quality of these services.

6.2.4 Project Management

The specification should clearly define the expectations of the customer with regard to project management. For example, the document should present the timescale within which the name and contact details of the vendor’s project manager are to be provided. This may also include a requirement for the project kick off meeting to take place within a specific number of days after order placement, the objectives of the kick off meeting, the frequency and location of subsequent meetings, and the frequency and requirements for any project reports and updates to the timing plan. It is often beneficial to specify that the project manager will provide details of the project team, including any major subcontractors, at the kick off meeting and confirm the project timing plan within a short period following this meeting. There are often changes to a project once the work has commenced, and it may be worthwhile to specify how the customer and vendor will decide on any changes. This includes the level of authority required from the customer side, as well as recording and reporting requirements to ensure there are no disagreements related to variances in cost as a result of these changes.

6.2.5 Design

In this section, the specification describes the method by which the design is to be developed, including any CAD tools. The section should include the customer’s need to review designs prior to manufacture, if appropriate. It may be beneficial to require the development of a functional design specification (FDS) as the first stage of the project, with appropriate customer reviews and approvals, prior to the commencement of any manufacture or software development. This may include the requirement for a failure mode effect analysis to identify risks within the project, potential solutions to mitigate these risks and the party responsible for providing these solutions. The FDS provides a detailed specification of exactly what is to be provided, the planned performance of the equipment and how it is to be operated. The specification should explain any requirement to review the safety aspects of this FDS, particularly if specific safety personnel from the customer side are to be involved.

6.2.6 Manufacture and Assembly

The customer may wish to request certain standards, such as company standards, are applied to the manufacture of items within the scope of supply, including the software. The customer may also have specific standards for equipment or manufacturers of equipment. These must be provided, either at this stage of the specification or in the design stage. The customer may also wish to gain access, subject to reasonable notice, to view the system during manufacture and assembly, in order to view progress, and the customer should state this requirement within the specification.

6.2.7 Predelivery Tests

Prior to the shipment of the system to the customer, the vendor normally performs tests to ensure the system meets the customer requirements. These are known as the factory acceptance tests (FAT). The complexity and completeness of these tests is very dependent on the automation system to be provided and the scope of supply provided by the vendor. The tests should be designed to determine if the vendor has met the criteria required by the customer as detailed throughout the specification. The tests therefore should include an overview of the system and the component parts, as well as the overall operation and functionality.

The performance of the system should also be tested. This can range from simply the striking of a welding arc on a welding system, with the customer being responsible for the fixtures and programming, to the full operation of a system for a number of hours to prove the functionality, cycle time, and reliability. In the latter case, the customer must be prepared to make product available to the vendor both to develop and test the system, as well as the FAT. The customer should also specify who will operate the system for the tests and the period, or number of parts to be produced, to define the length of the tests. If free-issue equipment is involved within the project, the impact of this on the performance of the system must be considered. Also the consequence of any failures during the FAT, in particular how the FAT should proceed, must be specified. The specification should clearly define the actual tests to be performed, especially those that involve a measure of performance such as cycle time, reliability or quality. These are discussed further in Section 6.3.

Defining the FAT can be a challenge. It is important to undertake tests, with appropriate timescale and detail, to provide a reasonable indication that the system is performing to the specification. However, the test condition is not the real production situation, and therefore, the tests should not be so onerous that they cannot be realistically achieved.

6.2.8 Delivery

If there are any specific issues related to delivery, these should be identified in the specification. This may relate to the notice period required, the time of arrival, the offloading and positioning of equipment, the sequence of the delivery for larger pieces of equipment or the responsibility for the return of parts or equipment that has been free-issued and the removal of packing materials.

6.2.9 Installation and Commissioning

It may be necessary to specify that the vendor must conduct a site survey to confirm the location of the system and to check access and the adjacent equipment. It may also be necessary to check the floor to ensure it is appropriate both in terms of condition and strength. If the customer does not specify that these are requirements to be conducted by the vendor, the vendor will assume the customer will cover these issues.

The specification should ask the vendor to provide a layout drawing confirming the positions of the equipment within the system and also the position of the services. This information should be checked against the existing facility. The customer can provide details of the existing facility and ask the vendor to check, or the customer can check based on the information provided by the vendor. It is worthwhile to identify the approach to be taken in the specification, particularly if it is the former.

The specification should also request an installation plan at an appropriate point in the project. This should identify the number of personnel involved, the hours they are planning to work, any assistance required from the customer and also any specific requirements that may impact existing production. If there are any constraints relating to access to the site, these should be stated as well. The specification should also state that the vendor is responsible for ensuring that all its personnel, and any subcontract personnel, adhere to all contractors’ site rules and health and safety rules in operation at the relevant site, including the successful conclusion of any appropriate training and the provision of all necessary safety equipment and personal protection equipment.

6.2.10 Final Testing and Buy-Off

Once the commissioning phase has been finished, there is usually a final test that, when completed successfully, provides for the buy-off by the customer and the handover of the system from the vendor to the customer. This test is often called the site acceptance test (SAT), and it follows a similar format to the FAT discussed in Section 6.2.7. The SAT is normally more detailed, with testing over a longer period or with higher volumes of product than is used in the FAT, because, at this stage, full operation under production conditions can be achieved.

The specification should describe the parameters for the tests, including the type and length of the tests. The SAT may consist of three stages, the first being an inspection of the equipment and documentation to ensure they are in line with the initial specification (URS) and any changes agreed throughout the project. The second stage is the operation of the system for a defined period to determine the cycle time, or throughput, and the quality of the product output. The final test might be over an extended period to determine the availability of the system.

As part of the definition for the tests, specification should identify the personnel who will operate the system. These may be the customer’s personnel, but there may also be a role for the vendor’s personnel, particularly during the availability test, because they will have better knowledge of the system and will be able to rectify any problems more efficiently. It is important to define the method by which the tests are to be measured and recorded to avoid any ambiguity. Further details are discussed in Section 6.3. Also, the actions to be taken in the event of a test failure must be defined. For example, the customer may wish the vendor to correct any problems and then restart the full SAT test or restart the relevant element of the SAT.

These tests are one of the most important elements of the specification. This is particularly true if the vendor is providing a “turnkey solution”, that is, they are responsible for the complete system. The FAT is important because it can avoid the need to correct problems on the customer side, which is preferable for both customer and vendor. However, the SAT is more important because this provides the final acceptance of the system. Without a clear definition of the SAT, there can be no clear buy-off criteria and, therefore, no measurements against which the vendor can be held accountable in the event that the system does not perform as anticipated. Thus, it is most important that the customer carefully considers this element of the specification and ensures that the defined tests and measures provide a realistic assessment of the system as it should operate in production.

6.2.11 Standby

A customer may request that the vendor retain one or more engineers on site for a period after the system has entered production. This may be limited to the period of the SAT, or it may be extended beyond this period to provide assistance to the customer’s engineers in the event of any problems. The requirement for standby normally depends on the complexity of the system and the experience of the customer’s engineers. If standby is considered necessary, it should be specified within the URS, including both the period required and the number of shifts to be covered.

6.2.12 Training

Training is an important aspect of any automation system. There will always be a need for some training, unless the system is a repeat of a previous installation. The training may include a number of different requirements. First, there may be a need for the customer’s personnel to attend robot training courses at the vendor’s premises. Second, the customer will need training on the actual system, covering both operation and maintenance, including preventative maintenance, fault finding, and error recovery. This latter requirement is often covered during the period of commissioning, SAT, and standby. It may be necessary to provide training to multiple personnel, both operators and maintenance personnel, across a number of shifts. If possible, the customer should identify the numbers of personnel from each category to be trained. It is important that appropriate training is included, and the customer should at a minimum require the vendor to specify the training that is included and when and where this will take place.

6.2.13 Documentation

The customer should also specify what documentation they expect to receive, including the desired format and number of copies. This might include an operation and maintenance manual to cover the instructions for safe use of the system, error codes and fault recovery procedures, recommended preventative maintenance, and also details of recommended spare parts and consumable items. A second documentation package might include more details of the as-built system, covering items such as electrical drawings, software listings, system certifications, and the FDS. It is important that the customer defines what documentation is expected as part of the overall delivery of the system.

6.2.14 Warranty

It may be worthwhile for the customer to specify the warranty period they expect for the system, particularly if they wish to have cover for a period longer than 12 months. The point at which the warranty commences should also be specified, which may be completion of the SAT, rather than the delivery date. The specification should also state any interest in a service contract for the period of the warranty, or extended beyond this period, covering annual preventative maintenance visits or breakdown callout cover. The vendor can be requested to include these items within the proposal, either as standard or as an option to the main price.

6.2.15 Other Items

The URS should identify the main customer point of contact, including all relevant contact details. This may be multiple personnel, such as engineering and purchasing, as appropriate. If multiple personnel are listed, the responsibilities should be clearly identified to direct the vendor to the appropriate contact point. Also any preferred equipment vendors should be identified if appropriate. Relevant standards should be specified if not already covered, and any customer specific standards should be included in the package sent to the vendors. The anticipated timing for the project could also be included if the planned production start date is known and this information is not covered elsewhere.

6.3 Buy-Off Criteria

The specification should clearly define the tests to be performed, particularly those that involve a measure of performance such as cycle time, reliability or quality. The definitions must include the period over which the tests are to be run and the measurements to be made. The URS should include the calculation for linking these measurements to defined performance parameters to avoid any misunderstanding or ambiguity, because this can lead to difficulties at the point of buy-off.

For example, the system could be run for a period of one shift (e.g. 8 h), operating at 100%. The output would be checked to determine the quality produced and identify any rejects. The check compares the product against the defined quality standard, which may involve dimensional checks or, if a visual quality is required, against an agreed standard, quality part. In the latter case, this is often called the “golden part”. The downtime would also be recorded, including the source of the downtime. The results would be compiled, as follows:

 TO = Total output

 QR = Number of reject parts

 TT = Total time

 DV = Downtime due to Vendor supplied equipment

 DO = Downtime outside of Vendor supplied equipment

This would then allow the production rate of parts with the correct quality to be calculated:

Productionrate=TOQR/TT.

si1_e

The Availability could also be calculated:

Availability%=100*TTDODV/TTDO.

si2_e

The above calculation is intended as a simple example. It may be necessary to include other elements in the assessment and the calculation. It may also be necessary to specify other buy-off criteria to correctly assess the performance of the system. The length of the system's operating time for the buy-off is very dependent on the type of application and the production rate. It should provide a reasonable test of the system, covering both capability and reliability.

6.4 Covering Letter

The URS could be accompanied by a covering letter that can address items not covered within the specification. This includes specific items such as the timing of the proposal stage, including any arrangements for visits to the customer site, the desire for any vendor presentations and potentially when the order is expected to be placed. The cover letter should also state the deadline when the quotes are to be received. In addition, it should outline the customer expectations regarding the responses from the potential vendors, or what the customer expects to see within the proposal. This may include:

 Timing plan (from order placement to full production) including significant milestones

 Outline of the system design, including a layout drawing and main dimensions

 Details of the main items of equipment

 Description of the modes of operation, such as start up, production, maintenance, and servicing

 System throughput and availability

 Any limitations of the system

 Details of any proposed subcontractors and the equipment/services they are to provide

 Any specific floor and foundation requirements

 Services requirements (including location on the above layout)

 Price

 Acceptance of the customer terms and conditions, which should be included in the package

 Any exclusions

The anticipated delivery date or start of production date should also be mentioned if it is not covered in the URS. It would also be appropriate to include the payment terms for the project if they are not covered elsewhere. Additionally, the cover letter can ask the vendors to provide details of any reference sites performing similar applications.

6.5 Summary

The URS is an important document because it defines what the customer wishes to purchase. The intention should be to provide all the information needed by the vendors in order to develop a proposal to meet the customer’s requirements. The URS therefore provides a standard against which the offers from the different vendors can be assessed, and it provides greater reassurance that the vendors are all quoting against the same requirements.

The URS not only assists the customer, but it also assists the vendors because they are provided with a clear description of the requirements of the project. The more experienced vendors will welcome this document because it does ensure a consistent basis for quotations, thus removing the opportunity for some vendors to provide low prices based on assumptions regarding the scope of supply and then potentially winning the project without the same content as other suppliers (see Chapter 8).

The URS also provides protection to the customer in the event that disputes regarding the scope of supply arise later. The clear definition of the buy-off criteria is a key element of the URS because this ensures that there are measurable parameters to be used in testing the system prior to acceptance. If these are defined prior to quotation, the vendors are aware of what will be required, and they can therefore include the costs necessary to cover this work.

For these reasons, the customer should develop a URS for all projects. This may be difficult for some customers who have less experience with this approach or the application of robots and automation. Appendix provides an example of a typical URS and cover letter. If new to the process, the customer might benefit from bringing in an external resource to assist with the development of the URS. Although there will be costs associated with this external resource, the reduction of risk and the related financial consequences often outweigh this investment.


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