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Food – Biscuit Capper – Burtons Biscuits, Llantarnam – 2021

Capping Machine Upgrade

The Project:

Burtons Biscuits tasked UCS Automation with a biscuit capping machine upgrade as the existing system was becoming more and more expensive to maintain. The existing system had a single motor and was mechanically cam driven for all processes, but was being upgraded to a motion controlled system. The new system included, not only ten servo axes but also a dedicated safety system for the line.

The production line was suffering poor operating efficiencies, due to the amount of mechanical maintenance required. Maintenance was becoming more regular and the machine down-time was increasing which resulted in less product being manufactured.

Surveying the Project:

We spent a lot of time understanding the operation of this machine before we started any work on the capping machine upgrade, the details are in Understanding the Process.

We had a couple of concerns following the survey, so needed to address them for a successful project

  • Could we accurately recreate the mechanical cam profile for the jam depositor?
  • Would there be any issues with the shuffleboard inertia?
  • Could we synchronize all the axis accurately?

To try and deal with these issues, we extended our initial survey in order to capture more data. An ethernet encoder was used to log the existing cam positions because we needed to get an accurate profile to work from. We logged and plotted the positions, giving us the motion profile for the complex cam system. This meant that the software development would progress much faster, as we didn’t need to develop a completely new profile for the machine.

The Existing System:


Our project engineer began work on the new control system, starting with the general arrangement and electrical layouts. These were checked with our site findings and when we were happy, issued the build order to our in-house workshop. Whilst the control panel was being assembled, our project engineer was working on the software development.

The Control System:

The client used Rockwell Automation’s Allen Bradley line of PLCs as standard, so our solution needed to use it too. We decided to use a GuardLogix PLC, ArmorBlock remote I/O, PanelView Plus 7 HMI, Kinetix 5500 servo drives and Powerflex 525 inverters. We used the ethernet protocol to issue commands and monitor the safety and alarms, allowing us to minimising the wiring requirements. The PanelView Plus 7 HMI was a 10.4” colour screen, allowing the operator to control the active elements of the process, monitor the machine status and adjust operation parameters. It also provided detailed warning and fault information that was useful during commisisoning, but allows the operators and maintenance teams to address issues quickly in production.

Construction, Installation & Commissioning:

So we could debug the control panel and software, it was put under test in the workshop before the site installation. The aim was to minimise the commissioning time on site. With only a small window for production shutdown we had to deal with all forseeable issues in advance.

During April 2021, our electricians removed the existing motor,  mechanical linkages and cam profilers. They installed the new panel onsite, along with the new servo motor system, wiring and mechanical adaptors, inlcuding new drive shafts. Our project engineer arrived on site at the end of the installation and began commissioning the day of the completed install.

Discussions with the machine operators and engineering team throughout the process enabled the project engineer to commission the system quickly. The timings and positioning that we couldn’t do in advance were sorted and a couple of modifications were added to improve the machine.

Overall the client was very happy with the delivery, and has requested a similar upgrade to a number of the other lines on site.

Our Services:

We provided the following services for this project:

  • Electrical AutoCAD design drawings. See our Design page
  • Control Panel Manufacturer. See our Manufacture page
  • PLC & HMI Software design. See our Software Design page
  • Operation manual
  • Risk Assessments and Method Statements for the installation
  • Disconnection and removal of the existing mechanical system
  • Installation, Testing and Commissioning of the system. See our Installation and Commissioning pages

Capping Machine Upgrade photos:

Understanding the Process:

We needed to learn and understand the operation of the capping machine to upgrade the control panel and software required to operate it, so we divided the process several, smaller functions.

A) Mechanical:

The existing mechanical system used chains, linkages and cams and was operated from a single motor. There were nine rotation points on the machine, meaning we needed this many servo motors on the new design. We also needed to consider the mechanical work to install and mount the new motors. We also needed to log the cam profile before we continued any further work.

B) Shuffleboard:

The shuffleboard recieves row of lids and bases and adjusts the order to produce columns of alternating lids and bases. The capping process needs this to work correctly. We had to consider the start and stopping times for the shuffleboardas the inertia of it prevented immediate start stop action. The jam and capper timing needed linking to this process. Too fast would result in too many biscuits in the holding area but too slow would cause shortages.

C) Holding area:

Immediately following the shuffleboard is the holding area, it is a conveyor belt with guide rails to align the lid and base columns. It also needed to hold enough product to keep a consistent product flow. There are also a set of sensor in this area, checking for the order of biscuits in the zone. The software monitors for lid holes and solid bases and flags an operator if the ordering is incorrect, allowing the operator to correct the issue and prevent the line from losing synchronization.

D) Rotodex Rough Spacer:

The rotodex rough spacer is a rotary axis with pins on and rotates at the end of the holding area. It processes single biscuits giving a rough space for capping alignment, but if it is too fast or slow and the biscuits will only pass partway through, breaking the biscuit. This causes both lost product and time to rectify. This feeds onto the capper conveyor.

E) Capper conveyor and rotodex fine spacer:

The capper conveyor moves the bicuits down through the rotodex fine spacer, jam depositer and capper. We needed to consider the speed because if it is incorrect it will cause misalignment, resulting in lost product. This rotodex is roughly the same as the rough spacer, but pin spacing is much closer and retards the biscuits to get precise alignment for the jam depositer. As with the rotodex rough spacer this is speed critial, deviations would result in broken biscuits, missed jam deposits and poorly aligned lids.

F) Jam depositor:

The jam depositer uses a cam profile to add jam to the base biscuits and moves in both the horizontal and vertical plains. Firstly it moves towards the fine spacer and then lowers down in line with the base biscuit. The depositor then follows the base biscuit and the jam pump is activated, placing jam on the base. As the depositor approaches the end of the horizontal movement it quickly moves upwards to break the tension. The high speed prevents the base biscuit from moving. If it moves too slowly, the biscuit will move out of position and result in poor alignment for the capper, meaning waste product. This process is completely timed with no sensors to detect any issues. The jam depositor also operates via timing with an inverter driven pump, triggering needs to be accurate.

G) Capper:

This is similar to the jam depositor but only uses a vertical axis. It aligns with the biscuit lids then pneumatically picks them up and holds them in place. Once the jam filled base biscuit is underneath the lid is lowered onto the jam and released. There are a set of forks to align the biscuits, but no sensors.  The air pump also had to be timed correctly to prevent misplaced biscuits.

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