Building The Machine: A Bedtime Story
The following story is from my book Industrial Automation: Hands On (McGraw-Hill, 2013). I wrote it to illustrate how a machine or production line is concepted, purchased, designed, built and delivered. This is a pretty typical description of the procedures used in custom machine building and serves as a detailed synopsis of Mastering the Machine.
Warning: its kind of long and may put you to sleep 🙂
After a recent improvement in the business forecast the ACME Widget Company has discovered that they will need a new widget line within the year. Mark, a company Project Engineer, has been tasked with finding appropriate vendors for the equipment and getting the line installed and started up for production.
Mark’s first task is to define the requirements for the new production line. A meeting is held with the Engineering Manager, Production Supervisor, Quality Manager, Maintenance Manager and Process Manager. The company’s Vice President of Operations and Comptroller are also present.
The forecast for the next few years’ production is that about 100,000 widgets per year will be required for the first couple of years ramping up to between 150,000 and 200,000 per year for the next few years after that. In addition a slightly larger widget has been designed that will be put into production next year. This brings the total number of different kinds of widgets produced by ACME up to 7.
ACME currently works two eight hour shifts a day. The current two production lines produce about 70,000 widgets per year, the bulk coming off of a newer line installed about 5 years ago. This line produced about 42,000 widgets last year but was down for maintenance, repair or setup/changeover about 20% of the available time.
The total days worked excluding weekends, holidays and schedule shutdowns are 48 weeks x 5 days per week or 240 days per year. This comes out to 3840 hours per year of available production time. If the total downtime of 768 hours is subtracted this leaves 3072 hours of actual production time. Since 42,000 widgets came off of line B in 3072 hours this means the line averages about 13.67 widgets per hour.
The Production Supervisor says he is sure that the line was specified at 16 widgets an hour and had achieved 18 during the initial runoff. After some quick calculations the Quality Manager determines that the line is running at about 85% efficiency discounting maintenance, repair and changeover. If the additional 20% downtime is taken into account the efficiency drops to only 68%. Since the ACME company has an active Six Sigma/Lean Manufacturing program the Quality Manager notes that this would be a good subject for a Kaizen improvement project.
After more discussion it is decided that the specification for the line speed will be set at 18 widgets per hour. If the line efficiency can be raised to 90% this should allow for (3840 hours x 18 widgets/hour) x .9 efficiency = 62,208 widgets. This should easily accomplish the initial target of 100,000 per year but will leave the capacity short after about 1.5-2 years if the forecast is accurate.
The Production Supervisor and Maintenance Manager believe that if some of the current pneumatic actuators were replaced with servos setup time would be reduced by up to 50%. Since setup time is estimated to be about 40% of the total down time this could be a significant improvement. In addition several problem areas on the current line seem to cause most of the downtime.
The Quality Manager asks if data is collected to help determine the cause of line stoppages. The Production Supervisor states that data had been collected during several periods over the lifetime of the production line but not recently due to manpower constraints.
The Engineering Manager mentions that it would not be terribly expensive to implement a data collection system using the existing PLC on the line. In addition the information could be collected into a production PC located on the factory floor.
Mark has been noting all of these comments during the meeting. He asks the VP of Operations and Comptroller if a budget has been determined for the project.
The Comptroller has a report from the implementation of the line five years ago. The line had taken a full year to build and install from start to finish. It had cost in the neighborhood of 2 million dollars including facilities improvements, in-house labor and payments to vendors. At that time there had been a much larger engineering department and much of the system design and layout had been done internally including implementation of the packaging system.
The VP Operations says that he thought they would have about $2.4 million available for this project but that Mark would not have much access to internal labor. He mentions that he thought he could think of a few areas where costs could be reduced and would get together with Mark and the Engineering Manager the next day to discuss some of these ideas.
Mark used the company template to begin generating a Requirements Document for the new widget line. Many of the items such as electrical and mechanical specifications have already been included in the template so Mark starts by making a list of the requirements specific to this project. Information such as the line speed capability, packaging requirements, footprint or space requirement and dimensions of the widget including the new product are included. Much of this information has to be collected from different departments within the company.
Mark also knows that per company requirements he will need to get a minimum of three quotes from machine builders and integrators. Because of this the requirements documentation needs to be very complete to minimize questions.
Mark knows of several machine builders both locally and nationally that are appropriate for building the new widget line. The company that built Line B five years ago is from pretty far away but had done a decent job on the previous line. They were very large however and not always as responsive as he would like.
Another company had recently made a few sales calls on both Mark and the Engineering Manager trying to drum up new business. They were from the same city as ACME and had left some brochures with Mark describing some of the jobs they had done. The brochure looked very professional and had some nice pictures of some pretty impressive looking machines, but nothing looked very similar to what this line would look like.
There are two other large machine builder/integrators that Mark knows can build the line, again both very far away. After going online and checking out their website Mark decides to send quote requests to LineX, the company that had built Line B; LocalTech, the company that had called on them recently, and the Mammoth Corp, one of the two large national machine builder/integration companies.
Mark wrote up a fairly brief quote request with a description of the proposed line, a picture and description of the widget, and a statement that further information, details and specifications would be sent if the company would be interested in quoting the line. He e-mailed the request to all three companies and began further refining the requirements document.
Later the same day Mark received a call from Bill, the Applications and Sales Engineer from LocalTech. Bill asked if he could stop in the next day and take a look at the existing Line B. Mark replied that tomorrow would be fine and that he would have the requirements finished by then so that Bill could take them with him.
The next morning Mark received another call from Jack, the sales rep for LineX. Jack says that he will be in town early next week and he would like to stop in and meet with Mark at his convenience. Mark says sure and puts Jack on the schedule.
When Bill arrives Mark has him fill out a standard non-disclosure agreement with the receptionist. He then takes him out onto the plant floor, first picking up a set of safety glasses and earplugs. Mark and Bill spend about two hours watching the line run and discussing the operations. Bill asks several questions about hardware, sequencing and when the order might be expected to be placed. Bill also takes quite a few notes as he examines the line. Mark gives him a copy of the requirements documentation including a machine specification, Bill says it will probably be the end of next week before he can work up a quotation. Mark also gives Bill a sample of a widget directly off of the line for Bill to take with him.
The following week Jack arrives. Mark discusses the previous line’s operation and mentions the slow response of LineX to several machine issues over the past few years. Jack explains that LineX had undergone a reorganization and that they now had a separate service department and was much more responsive. Mark gives Jack the requirements documentation and a sample widget to aid in his quoting process.
Since Mark hasn’t heard anything from the Mammoth Corp he gives their sales department a call. He is connected to the regional applications engineer Steve, who explains that they have been inundated with quote requests and wouldn’t be able to make it out to look at the application for a couple of weeks. They set up a meeting for Thursday a couple of weeks later.
By the time Steve makes it out to ACME Mark has already received quotations from the other two companies. Steve says he should be able to turn a quote around in a week or so but that deliveries are running a bit long currently.
Two weeks later a meeting is set up with the same members as the kickoff meeting to discuss the quotations. The Mammoth Corp barely got their quote on the evening before the meeting making Mark worry about the comment Steve had made concerning long delivery.
The Mammoth Corp provided the most detailed and comprehensive of the three quotes. Much of it appeared to be boilerplate, but it was obvious that they had done their homework. It was accompanied by a nice cover letter and 3D renderings of what the finished system would look like. It was also the most expensive of the three quotations at about $2.2 million.
LineX provided a detailed quote also with pictures of Line B and detailed descriptions of machine operation. Improvements to the new line were also described including an innovative part flipping mechanism. The quote was the lowest price of the three companies at a bit over $1.7 million. Since the previous line had cost almost $1.6 million this seemed quite reasonable with the proposed improvements. Of course having built the previous line it was expected that LineX would be the least expensive of the three.
LocalTech’s quotation came in at just under $2 million. Like the Mammoth Corp the quotation included 3D solid models of the line. Details were also broken out into sections proposing improvements to both the original line and the new one.
It was obvious that LocalTech was very hungry for the job; emphasis on the local support was evident in the quotation. Assurance that the expertise required for the application was also written into the proposal.
After weighing all of the factors it was decided that a purchase order would be issued to LocalTech. Though the pricing was higher than that of LineX it was agreed that the local support could be valuable in the long run. Mark had called several of LocalTech’s references and it was generally agreed that LocalTech stood behind their work and really went the extra mile for the customer.
Mark drafted a Statement of Work (SOW) that effectively restated the items in the quote request and set out the tasks and expectations of both the vendor and customer.
Mark called Bill from LocalTech with the good news that they had decided to use them to build the new line. Bill stopped by later that afternoon with his engineering manager Jim to discuss the procedures that would be used to manage the project. During the discussion the conversation got around to payment terms and Bill mentioned that there might be a bit of a problem.
LocalTech’s requested terms were 40% down payment with order, 40% prior to shipment and 20% net 60 days after delivery, or 40/40/20. ACME had a standard policy of 30% down, 30% after receipt of 90% of materials, 30% after FAT and prior to shipment and 10% net 90 days after successful SAT. After a phone meeting was held between ACME’s buyer and the owner of LocalTech it was agreed to abide by ACME’s terms. A clause was written into the purchase order that the second 30% would be paid no longer than 120 days after initial parts requisitioning by LocalTech to help with cash flow.
A purchase order was faxed to LocalTech 2 days after the meeting and mailed one day later. LocalTech sent an invoice to ACME and payment was received 57 days after that.
A project kickoff meeting was held at LocalTech to discuss the application. Bill and Jim described the project and the quotation was presented to the project team.
Joe was assigned as the mechanical lead on the project. There were three mechanical project engineers at LocalTech and it was fortunate that Joe’s previous project was winding down since he had built a line very similar at his previous job. Joe asked if any documentation from the previous Line B would be available to leverage for the project. Bill said he didn’t think that Mark from ACME would feel comfortable giving them any solid models or CAD files since LineX had bid on the line but had not gotten the job. Everyone agreed that that would probably not be an ethical thing to do.
The first thing Joe had to do however was read the specifications. After asking a few questions about hardware choice restrictions he was ready to start work on the design.
Joe first generated a timing and device chart using his template. This was a Microsoft Excel template that was used by applications, mechanical, controls and software departments jointly to determine machine timing, pneumatic sizing and the actuators to be used on the machine.
The next step in the design process was to start designing machine assemblies. An assembly is a grouping of components to accomplish a specific task. It may consist of a simple actuator or something as complex as a multi-axis pick and place with mixed electrical and pneumatic cylinders. Though this could be decided arbitrarily by the mechanical designer, LocalTech had a standard procedure for deciding what would make up an assembly.
Joe decided that a Stelron chassis would be used for the movement of widgets around the machine. Widgets would be fed from a vibratory feeder or bowl onto a pallet on one corner of the chassis via a two axis pneumatic pick and place with gripper. After proceeding clockwise around the chassis through various assembly and inspection stations widgets would be removed at the adjacent corner after moving across three sides of the chassis. Empty pallets then rotated around to be loaded again.
Since the process would be mostly synchronous, some of the actuators would be moved by the chassis itself. Those that weren’t had to be dimensioned and sized to determine their capability and suitability.
All of LocalTech’s designs were done in SolidWorks, a 3D solid modeling program. Joe had worked on this platform for over ten years and was quite comfortable with it; in fact he had generated the solid model representations of the line concept for Bill.
Joe decided to spend a day or so downloading files from vendors for the chassis, actuators and other purchased components that would be used on the system. There were four additional mechanical designers at LocalTech for a total of seven mechanical licenses or “seats”. The designers acted as a resource pool for the mechanical department, filling in where necessary for the project engineers. After Joe had spent some time assembling a list of proposed components (preliminary bill of materials) he gave part of the list to a designer and downloaded the rest himself.
Most of the vendors for the major components had step files, a generic file format that worked across solid modeling platforms, available for their hardware. A few had only AutoCAD files in three views, so these would have to be turned into solid models.
With the help of the mechanical designer it took about three weeks to get all of the individual assemblies modeled.
Finite Element and Stress Analysis
After drawing all of the assemblies and floating them above the chassis locations Joe entered the estimated weights and dimensions of hardware into a spreadsheet and did some analysis on the expected stresses that would be incurred by the mechanisms, bracketry and framing of the main machine. Joe had a FEM (Finite Element Method) software package that allowed detailed visualization of where structures would bend or twist. This allowed him to produce stiffness and strength calculations that would help minimize and optimize weight, materials and costs throughout the machine.
Framing and Bracketry
With the FEM analysis done the mechanical team was able to attach all of the assembly models to the chassis. As with any design various interference points were found and brackets and locations had to be modified. One of the advantages of using a chassis was that locations were fixed; if there wasn’t enough space for an assembly one could simply ensure that the required space was available by leaving empty pallet stations. In one case a mechanically linked station had to be moved over one spot, the chassis was re-quoted by Stelron with no change in price.
Joe decided that most of the framing and brackets would be made of welded cold-rolled steel. Of course this had to be painted but was typically the least expensive option. An exception was the mounting for the vision system: Joe decided to use aluminum extrusion since the camera needed to be adjustable. A few of the sensor mounts were made of aluminum plate since load requirements were not high, the brackets were small and they didn’t need to be painted.
Joe also decided to use aluminum extrusion for the guarding on the upper frame of the machine. This way it would be easy to make doors and mount hinges and switches, also it was much easier to correct mistakes that might be overlooked during the design process.
After a mechanical design review with the customer, Joe and his mechanical designer started detailing the individual components of the machine for manufacturing. This involved breaking the assemblies down into their individual parts again and dimensioning, tolerancing and specifying finish and materials on two dimensional drawings. Some of this data could be put into a CNC machine directly but much of it would be made the old fashioned way by machinists on mills and lathes.
Much of the hardware was detailed here also; bolt and screw sizes and plate thicknesses were determined to generate the final Bill Of Materials, or BOM. Plate and tubing thicknesses sometimes had to be ordered oversized because of the skimming of material during the machining process.
Instructions for the machinists were also placed on the detail drawings, things like which pieces to stress relieve and whether assemblies had to be machined again after welding. This was especially important for some of the machine pads that needed to hold brackets completely parallel.
Electrical and Controls
Gordon had been at the initial project kickoff meeting and had also read the specifications. Most of his controls hardware brands were pretty well spelled out in the specifications and requirements documentation so nothing looked particularly difficult. ACME was pretty heavily specced on Allen-Bradley controls. The original controller had been an SLC 5/05, Most of what was being used in the industrial world nowadays was of the ControlLogix family. Gordon gave Mark from ACME a call and asked if it would be OK to use ControlLogix.
Mark didn’t know offhand but after a quick call to Jake the controls tech on the plant floor he had his answer. ACME did have Allen Bradley ControlLogix processors in the plant but since they hadn’t renewed their license they were about two revisions back on their software. Gordon assured him that would be OK since he had revision 17 on his laptop.
Gordon had met with Joe early in the design process to help him tweak the timing and device chart. They had agreed on the names they would use for the actuators and sensors and Joe had done a lot of the sizing of the pneumatic cylinders already. The first thing Gordon started working on was the I/O list which would dictate the layout of the controls.
One of the improvements LocalTech had proposed was using networked I/O on the machine to save space. They had used Devicenet and Controlnet on quite a few projects but Ethernet I/P based I/O was very cost effective and would be used on this system.
Since there were a couple of external systems including a bowl feeder, vision system and two packaging machines to be integrated, networking and distributing the I/O made a lot of sense. The vision system was to be a Cognex Insight smart camera which already had Ethernet I/P connectivity and a host of examples on their website. There was no controller on the vibratory bowl but the sensors were to be paralleled into a local node for data acquisition.
After calling the vendors for the two packaging machines it was discovered that one was an Allen Bradley SLC 5/05 so Ethernet I/P would be no problem. The other was a Siemens S7 Controller with ProfiBus capability but no Ethernet I/P. The interface between the controllers could be digitally “bit-banged” where inputs of one controller are connected to outputs from the other and vice-versa, or a ProfiBus card was available from ProSoft for the ControlLogix rack. After weighing the cost, speed requirements and integration time into the equation Gordon decided on the digital “bit-bang” approach.
Gordon finished his I/O list and started a simple single-line diagram to show power supplied to the various components of the system. Since there were a couple of 480VAC motors on the conveyors the and packaging systems, he drew a 3 phase 480V line and placed a box indicating each conveyor and the packaging machine underneath. There were quite a few 120VAC devices including the PLC, Vibratory Bowl, DC power supply and a computer utility port so he decided to use a single phase transformer to supply this power internally.
For safety all sensors were to be 24vdc so he placed a single line of 24v power under the 120vac row. For all of the boxes placed under these lines he placed approximate fuse sizes to get an idea of the total current draw of the system.
Like Joe, Gordon had a couple of electrical designers he used to generate his actual electrical drawings. After a meeting where he provided a designer his I/O list and single lines and described the system he began to consider his programming task.
After a couple of weeks the designer had generated a fairly complete set of drawings for review. Gordon used a red pen to “red-line” corrections onto the drawings, the designer made the changes and the drawing package was ready to review with the customer.
Software and Integration
LocalTech was a small company, so Controls Project Engineers did double duty on electrical design and software programming. This of course kept Gordon and other controls engineers quite busy but everyone took up slack for each other to make schedule.
While the designer was drawing schematics, Gordon started making flowcharts for his programming. As with most of the design functions at LocalTech there was a template for this. Microsoft Visio was used to draw logical statements and flow similarly to any computer program. Though PLCs did not operate in quite as linear a fashion as the usual Fortran, Basic or C programs since scanning was involved, the techniques used were much the same.
Automatic Code Generation
Another time saving technique LocalTech used in program design was a spreadsheet based tool. On the I/O spreadsheet where all of the input and output assignments were made there were a number of Excel macros written to generate AutoCAD descriptions for the designers and tags for the PLC and HMI. In addition to the inputs and outputs a column was dedicated to defining what kind of device the I/O point belonged to. Photoeyes and proxes, pushbuttons, solenoids, motors and even servo components were designated and internal program permissives, HMI buttons and indicators and even fault tags were generated.
LocalTech could program quite a few different types of controller, both PLC based and others, but one of the advantages of using Allen Bradley’s ControlLogix platform was that the usually graphical ladder logic could be programmed mnemonically. This meant that text statements could be used to generate an L5K program which could then be viewed graphically. The macros in the program would generate actual ladder logic rungs with tags in the correct locations and subroutines. This saved a tremendous amount of time since many of the input and output rung subroutines as well as faults and data acquisition/OEE subroutines and rungs were generated automatically. A generic PLC program template was then opened and all of these routines copied into it.
Auto sequence subroutines and other non-standardized logic still had to be created the old fashioned way but the flowcharts were quite helpful there. It always helps to plan the code out structurally first. By the time the electrical design review was held with the customer Gordon had made a good start on his coding.
Gordon preferred to use numerical values for sequence states. Bit-of DINT and State Logic techniques were often used by his peers at other machine builders and integrators but since Gordon had been at LocalTech the longest of all of the controls engineers he was able to institute this as a standard.
Each sequence was contained in its own subroutine called by the station routine. The line was logically divided into zones and stations agreed upon with his mechanical counterpart Joe.
HMI tags were also generated by the spreadsheet and imported into the program software. An Allen Bradley Panelview Plus HMI was used for the ACME line; sometimes customers wanted the extra capability of an actual computer for the system but it was not required for this application.
By the time Gordon got to the HMI part of his programming and design, Joe had created a number of renderings of the entire line and some of its stations. Joe was able to easily export these as .dxf files. Gordon opened them in his AutoCAD program, re-exported them as bitmaps to Microsoft Paint so that he could simplify them. He then imported his bitmaps into the HMI program.
As with the PLC program there was an HMI template. It had a main screen, a couple of sample station screens, screens representing PLC I/O, OEE and data production screens, standard servo screens and faceplates. This gave the programmer a good jump on creating the application.
There were several external systems to the main line. The vibratory bowl fed a conveyor which fed the chassis, the chassis fed its output to a conveyor which passed through a packaging system including a case erector and filler. The Cognex vision system also had to be tied into the system, triggered and timed with a reject mechanism for failed widgets.
Meetings had been held with the packaging machine and vibratory bowl manufacturers when purchase orders had been placed by LocalTech. Gordon had received quite a bit of preliminary information from these vendors but final drawings would not be completed until shortly before delivery.
LocalTech had a close relationship with a local machine vision consultant who specialized in Cognex. An order had been placed based on the number of hours Bill had thought the project might take to be set up. Gordon also had experience with Cognex vision so after the system was initially set up he could take responsibility and maintain it.
As parts started arriving from the vendors after being ordered by the design teams they were stored on shelves next to the assigned assembly area. At any given time LocalTech generally had several projects under way and it was important to place parts and assemblies in a common location so they could be easily located.
Much of the main structure of the line was supported by the chassis and conveyors, but a welded frame was needed at the two ends of the chassis to mount a pick and place assembly. The frames were welded together in an area off of the machine shop and then finished in the CNC machine.
Most of the brackets that provided station structure were done in the same way. The frame was then stress relieved using a vibratory stress relief unit and the bracketry was done in an oven. The pieces were then masked and sent out to be painted since LocalTech did not have a paint shop. When they arrived back at the receiving dock they were immediately tagged and brought to assembly.
Many of the other mechanical assemblies were simply made in the machine shop and most were to be bolted together. As with the structural pieces when they were completed they were tagged and brought out to the assembly area.
Several pieces were very tightly toleranced and had to be verified on the new CMM (Coordinate Measuring Machine). In tolerance parts were brought out to the floor while out of tolerance parts were either reworked or remade.
After the schematic drawings had final approval from Gordon and ACME the panel shop was given the released drawings. Components had been arriving for more than a week but there were still not enough to warrant starting the panelbuilding process. Gordon gave the vendor a call and found that they were still waiting for a connector for a servo drive before they could ship complete. Gordon knew the electrical guys were eager to get started so he told the controls vendor to go ahead and ship what he had.
Since most of the parts had arrived the backplane was laid on a couple of sawhorses and a pencil was used to carefully mark where the dinrail, wireway and major components would be mounted. Holes were drilled and tapped for components and through drilled for the rivet mounted wireway. All of the major elements were then mounted to the painted steel backplane to be wired.
LocalTech had an employee who had done all of the panel wiring since the company had started. There were several electricians who wired and plumbed machines but all panel wiring was left to Mieko since her wiring was beautiful to behold. Since she had small fingers and an eye for symmetry and distance she was well known as a fastidious and fast worker.
Larger AC wiring was used for all of the 480VAC elements. This was color coded brown orange and yellow so that phases could be identified easily. AC wiring was then done in red and white and DC wiring in blue and white-striped blue wire. All wiring was routed through wireway and made neat 90 degree turns, adhesive wrap-around labels were consistently located about 1/8” from terminal blocks and care was take to ensure different voltage levels were not routed together.
The chassis had been on the assembly floor for a couple of weeks before the frames and structural components were delivered from the paint shop. The assembly crew had put together several of the subassemblies and stations on worktables and now they could start putting together the whole machine.
The electrical enclosure was a low double door cabinet that mounted to the frame at the entry to the chassis. Holes were punched in the cabinet before mounting it to the frame and the fully wired backplane was bolted inside.
After all of the major stations and assemblies were mounted to the frame and chassis the guarding structure was attached to the top of the machine. Lexan panels and doors were inserted and much of the main chassis was complete.
The conveyors had arrived at about the same time as the vibratory bowl and chassis but the packaging machines were running a bit late on delivery. Gordon and Joe had attended runoffs at both manufacturers and had found a number of items that did not meet ACMEs specifications. While the manufacturers had agreed to fix most of the issues a few would have to be handled by LocalTech.
Conveyors and auxiliary machinery were placed into position and a laser transit was used to locate and level components to each other. Machinery was then lagged to the floor and the rest of the guarding put in place tying the production line elements together.
The electricians and Mieko began wiring the sensors, valve banks and other components back to the main panel. Plastic wireway was mounted to the framework of the machine and guarding to provide convenient routing for cables and hoses. Quick disconnect cables were used in various spots so that the machine could be easily disassembled and shipped later.
Startup and Debug
Assembly was finally ready to turn the machine over for startup and the project team was assembled on the assembly floor for a safety briefing. Gordon and Joe handed out a list of potential safety hazards and a startup checklist to each of the team members. This reiterated lockout/tagout procedures and stated that only Gordon and Joe were authorized to power up and operate the machine until debug was complete.
Mechanical and Pneumatics
Before applying power to the machine air was applied to the pneumatic quick disconnect. A technician went to all of the actuator valves and ensured that they were plumbed correctly by manually actuating the valve with a screwdriver. Flow controls were set to ensure that cylinders operated at the appropriate speed with Joe’s supervision. They were then locked down to ensure they wouldn’t be moved inadvertently.
Gordon did a basic electrical check to make shore that there were no short circuits phase to phase, phase to ground or + to -. Fuses were all checked against the schematics and the fuse holders and breakers were left open. Gordon had everyone stand back, closed the main enclosure door and turned the main disconnect on.
Gordon then sequentially engaged all of the branch fusing and breakers starting from the highest values closest to the disconnect. Since he had checked all of the circuits himself using his meter he knew there should be no problems, but it was always safest to follow good practices.
All of the E-stops were pulled to their disengaged positions and Gordon pushed the Power On/ Reset button. The button illuminated, the MCR engaged and the machine was finished with its power up procedure.
Before the program was downloaded all of the auxiliary equipment was powered on and tested. The conveyors were driven by VFDs so the keypad on the front was used to turn the conveyors on. This ensured that the motors would turn in the correct direction; if they didn’t it was easy to go into the parameter settings on the drives. If motor starters had been used the phases to the starters would have had to be swapped. Speed control of the conveyors was need though so VFDs had been chosen.
The vibratory bowl was quite simple and started right up. The filler wouldn’t seem to run no matter what was done so Gordon arranged for a technician to come out the next day.
When the technician arrived he explained that the E-stop circuit had to be wired into the main line and the jumpers for auxiliary equipment had been inadvertently left out. After the jumpers were in place and the E-stop circuit wired into the line the technician ran the filler through its paces.
After all of the stand-alone elements had been set up and exercised it was time to begin integrating the entire line.
The standard equipment layout for LocalTech included a computer utility port on the front of the enclosure. This was manufactured by Grace Engineered Products and was somewhat generically called a “Graceport”. This was a standard duplex electrical utility outlet with a GFCI, it also included a communications port that could be ordered in various configurations. This one had an RJ45 Ethernet port connected to an internal Ethernet switch linking the PLC, HMI and Ethernet/IP I/O devices.
Gordon first used a BootP utility to set the addresses on the PLC and HMI. After communications was established he downloaded both the PLC and HMI programs.
As usual there were a few indicators on the HMI that didn’t connect to the right points in the PLC. These were easy to spot since they showed up as dark blue spots on the screen, Gordon corrected the addresses and went through all of the screens to ensure that everything flowed properly.
Usually Gordon used an emulator to test the PLC and HMI programs during the writing of the software but there had simply not been enough time. Since this was a smaller line it was really just as easy to check the software on the machine anyway.
Gordon brought up the I/O screens and showed the electrician how to navigate the HMI. He gave the electrician an I/O list and had him go to every sensor and actuator and ensure they worked all the way thorough the system.
Since the E-stop circuit had been checked and actuator movements adjusted Gordon then placed the line in manual mode. After checking the light stack and ensuring the yellow light was illuminated he went through the process of pressing all of the actuator buttons and ensuring movement. He started and stopped the chassis drive without the clutch engaged and then went ahead and restarted to observe the chassis operation. So far everything had worked without a hitch!
As a standard part of the PLC template LocalTech had a mode called “Dry Cycle”. This allowed the line to be operated without any product loaded just to exercise all of the actuators. The next morning Gordon decided to let the machine dry cycle for a few hours just to make sure that nothing was loose. After lunch the electrician told Gordon that the machine had run pretty continuously except for a prox that had needed to be adjusted and a loose bolt on a pusher. That afternoon it was time to load a few widgets into the machine and see how the machine reacted.
It took nearly two weeks of work before Gordon and Joe were satisfied that the machine was ready for full automatic operation. The vibratory bowl was loaded with widgets provided by ACME and they ran the machine for several more days.
Mark, the Project Engineer from ACME, had been talking with Gordon and Joe regularly since the start of the project. He had stopped by during the assembly of the line and stopped in again to watch the operation of the line in Auto. Everyone agreed that it was time to talk about running the Factory Acceptance Test.
Factory Acceptance (FAT)
Mark and the Production manager along with two experienced line operators from line B showed up bright and early Monday morning. The Factory Acceptance Test for this line was to be a continuous four hour run with at least 95% up-time and full specified speed of 18 parts/hour.
A major element of the speed requirement was that the operators had to perform their tasks in concert with the machine. Exceptions for bathroom breaks and machine maintenance were a part of the overall plan, but for this run the line operation needed to be continuous. Rejected parts would also be checked for conformance and known bad components inserted by the operators.
Check sheets with a list of performance criteria had been created by ACME with input from LocalTech for both this runoff and the subsequent one after installation.
After a nearly flawless run the maintenance technicians and operators ran the machine through some manual and calibration procedures as part of their training process. Mark had no qualms in signing off the line as being ready for shipment.
Site Acceptance (SAT)
After the machine had been shipped and installed the site acceptance test was performed similarly to the FAT. An 8 hour run (a full shift) was performed using additional operators from line B. The line seemed to run even better with over 98% up-time.
During the initial startup at ACME there had been some issues with the Cognex vision system. Gordon had found out that light from the Mercury Vapor overhead lighting was casting a reflected beam into the inspection area; a quickly fabricated shield was placed over the guarding and documented for inclusion in the maintenance manual.
After the FAT the line was taken apart into its individual machines. The original crating for the vibratory bowl and packaging machines had been set aside and were brought back out for re-shipping.
The main chassis was unbolted from the floor and placed on wooden 4”x 4” skids. The machine was picked up one end at a time using a fork lift to slide the skidding underneath and the legs bolted to the skidding.
Since the machine only had to be shipped across town it was loaded onto a local truck without any crating. Straps were used to tie it off and the other machines and various boxes of odds and ends were loaded on the same truck.
Contract Millwright and Electrician
LocalTech had formed a relationship with a local mechanical millwright and industrial electrician for installations. They met the truck at the ACME plant along with Gordon and Joe and assisted with getting the crates and skids to the installation area.
Unlike the assembly area at LocalTech, production areas did not always have overhead bridge cranes or forklifts to lift heavy equipment. The millwright had assisted with the installation of many of LocalTech’s machines in the past and could be counted on to treat the equipment carefully.
After getting the equipment into the right location on the plant floor the crating and skidding was removed. The machines were all re-leveled and bolted to the floor using a hammer drill and concrete anchors. Special concrete pads had been poured to drill into for part of the framing.
With the help of LocalTech’s electrician and the industrial electrical contractor the machines were reconnected. New conduit was run from the main panel to the individual machines for power, this had been temporary at the LocalTech assembly floor.
ACME’s facility engineer came out and ensured that power and air was dropped to the proper location for the line. The machines were powered up much more quickly than during the original startup since the system had already been checked thoroughly. After Gordon and Joe did a quick check of the machinery they powered up the line and prepared for SAT.
After the Site Acceptance Testing two weeks went by while ACME performed training and qualification of the equipment. Mark spent nearly all of his time out on the floor as two shifts had to be brought up to speed. After two weeks the line went into full production as Line C.
The First Three Months
There was no doubt that Line C was faster and more high-tech than Line B. Despite the fact that LineX had more experience with the widget manufacturing industry, LocalTech had proven to be very technical and detail oriented.
The OEE (Overall Equipment Effectiveness) screens on the HMI were very helpful in determining the causes of stoppages in specific areas of the line. The Quality Manager in particular mentioned that he would like to see this implemented on lines A and B also if the budget would allow for it.
Gordon and Joe had needed to come by several times during the first few months to make some minor adjustments and software changes but overall the project had turned out to be a huge success. LocalTech would be seeing more business from ACME on future projects for sure!
About nine months into the operation of the line one of the AC motors on a conveyor had stopped working. LocalTech was called and the motor sent to the manufacturer for replacement. Since the motor had been on the recommended spare parts list it was quickly replaced and production resumed.
One of the photoeyes on the outfeed conveyor had also mysteriously been found broken in the morning twice (after night shift of course…). Mark had a guard fabricated and bolted over the sensor and anticipated no further issues.
And they lived happily ever after, THE END. (I added this part for the blog, it’s not in the book. Now go to sleep.)