Preventive Maintenance of Industrial X-ray System – A Must! | North Star Imaging

Preventive Maintenance of Industrial X-ray System – A Must!

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Stephanie Vinger

Service & Technical Training Manger

Industrial X-ray imaging is commonly used as part of design validation and quality control processes across many industrial applications including Aerospace, Automotive, Electronics, Medical, Pharmaceutical, Military and Defense. Similar to medical doctors and specialists checking for cracks and fractures in bones, industrial radiographers and manufacturing engineers use X-ray images to check for cracks and flaws or defects that are not visible to the human eye from the outside of the products being manufactured. 

X-ray images are acquired by placing a product/object on a stage between an X-ray tube and X-ray detector.  As the X-ray beam passes through the object, the X-ray energy level is attenuated in proportion to the material thickness, inclusion or voids within that object. This results in 2D or 3D images that are used for further evaluations and inspections.   

The use of X-ray techniques to inspect the integrity of industrial products dates back to the turn of the century.  As the industrial world continues to evolve, the technology improvements associated with the creation of the X-ray image, and modern computer hardware and software improvements, are allowing the X-ray imaging process to be carried out at higher speed and higher resolution. The result is higher efficiency, improved quality, and reduced overall manufacturing and operating costs. 

Today, not only do we rely on the continuous development of new imaging technology and design innovations on the industrial X-ray system to increase product quality and performance, we also depend on them to achieve planned production capacity and manufacturing throughput.  Equipment uptime in general, has becomes one of the most critical KPIs/Key Performance Indicators to measure manufacturing efficiencies today.  In a highly competitive market sector, significant capital investments on equipment reliability and maintenance are required to manufacture goods of almost any economic significance. The result of these investments can sometimes be a fundamental element of competition among companies and nations. Any event that slows or interrupts the manufacturing process or degrades equipment reliability, will impair the competitiveness of any manufacturing enterprise.  

Industrial Digital Radiography System Components

An industrial Digital Radiography system is comprised of several major components.  On the source side, there is an X-ray tube that generates the X-rays; a high voltage generator that provides the necessary voltage to power the X-ray source; a high tension cable that connects the generator to the X-ray tube; a controller that provides dedicated control of generator functions and power adjustments; and a water or oil based cooler/chiller to provide cooling medium to ensure optimum X-ray tube protection and longevity. 

On the imaging side, there is an image capture device.  There are two major variants of digital image capture devices, flat panel detectors (FPD) or a high-density line-scan detectors, more commonly known as the Linear Diode Array (LDA). 

To complete the system, there is a structured manipulator where the tube and detector are mounted which allows for multi-axis motion; a material handling apparatus to hold the object being inspected, a shielding chamber (the cabinet), and a computer work station for image reconstructions and data analysis.  

Proactive Preventive Maintenance of industrial X-ray systems

Just as preventive care is essential in maintaining healthy patients, the same can be said of industrial X-ray equipment.  Industrial X-ray equipment suppliers and service providers often offer preventive maintenance contracts to help minimize downtime and improve the overall reliability of the system.  It is important to recognize that preventive maintenance, when done right, not only helps identify unusual machine wear, but also operator misuse which could then result in premature equipment failure or safety concerns.

A routine preventive maintenance of an industrial X-ray system includes, but is not limited to the following cleaning, adjustments, verification and testing activities:

  • Tube Cleaning

An X-Ray tube, in essence, is a vacuum tube that converts electrical input power into the intensity of X-rays.  As with any vacuum tube, there is a cathode, which emits electrons into the vacuum, and an anode to collect the electrons, establishing a flow of current, creating an X-ray radiation beam.  X-ray tubes come in 2 general forms, Sealed and Opened.  Sealed tubes contains all components necessary to produce X-rays.  It is generally maintenance-free, but has a shorter lifetime and requires replacement at some point.  Opened tubes use vacuum systems to create a vacuum within a steel tube enclosure.  Due to the fact that the tube’s enclosure can be opened to replace consumable parts such as filament, target, socket and O-rings, this type of tube can offer almost unlimited lifetime.  Opened tubes are taken apart during preventive maintenance service.  The tube enclosure is wiped cleaned inside and out of debris, and O-rings are replaced.  Filament and target are inspected, adjusted if necessary and sometimes replaced.   The tube is fully reassembled after cleaning.  The service technician then cleans, sets compression and re-applies dielectric grease on all high voltage cable connections between the tube and the generator, inspects, cleans and adjusts generator as needed, tests and verifies vacuum system and cooler operations, and ensures all fluids are at optimal levels prior to running factory-set warm up and tuning procedures of the entire X-ray set.   Adjustments and settings are made using vendor supplied software application to attain optimal performance at different power levels. 

  •  Mechanical, Electrical and Safety Testing

Trained service technicians typically run through a series of electrical and mechanical testing during routine preventive maintenance service of an industrial X-ray system.  This include testing to ensure all safety interlocks, warning lamps, light curtains and sensors are functioning properly.  They also inspect and verify all mounting hardware are securely tightened, check for proper cable drapes, and secured wire terminations. 

For system with motion manipulation, technicians will inspect and verify motion control operation, driving each axis to its home position, and verify that all crash limits are sets accordingly.  Limit sensors, motors and encoders may be adjusted as needed.  Manipulator rails and gears are greased and wiped clean.   

  • General Performance and Functional Verification

A preventive maintenance service visit typically starts with system operation verification so the technician performing the service has a baseline reference of the system performance level.  This is typically accomplished by running an image quality check (using a known reference object).  Once the X-ray system has been disassembled, cleaned and reassembled, a second image quality check is done to ensure that the same, or sometimes better quality image is obtained.  Alignment of the tube and detector are typically verified at this time, and adjusted and optimized if needed. 

Depending on the service program, it is not uncommon to expect service technician to verify the digital radiography computer workstation functions, which may include updating DR application software and installing software patches during maintenance visits.

A preventive maintenance service visit for an industrial X-ray system is always completed with a radiation survey of the system.  This survey verifies that any work performed during the maintenance visit did not cause any performance changes that could result in radiation leakage. 

It is common for the technician performing the service to have a checklist of all the relevant tasks that need to be done for the specific model/system being serviced.  Most service providers require their technicians to leave a copy of the completed checklist or service report with the end users at the completion of the service visit.  

Qualified service technicians are typically trained to also pinpoint potential issues, and will identify parts that are deteriorating or wearing down that may eventually become unusable.  The service report may also include suggestions of replacement parts to keep on-hand, as well as recommendation of activities for end users to perform to help the X-ray system stay in good working order between routine maintenance visits.

Benefits of Preventive Maintenance Service Contracts

While most service providers would offer preventive maintenance services without a contract or agreement, a maintenance contract may be one of the best investments an organization can make to protect against unexpected loss due to costly repairs and downtime.   Benefits a typical Industrial X-ray System Preventive Maintenance Contract could offer are shown as follows:

  • Guaranteed pre-paid services during the contract term.  Each contract should include a number of service visits within the contract period.  This means the end user can arrange the service requests with the provider without having to go through the purchasing and approval process each time.
  • The ability to plan for downtime with pre-planned maintenance schedule. 
  • Priority service response.   This means the end user can receive emergency on-site assistance quickly when crises arise.
  • Discounted pricing for parts and components purchase.
  • Discounted labor rate for other services.  Some service contract programs may also waive industry standard call-out fees (rescheduling fees, travel time, etc.)
  • Dedicated phone or remote support line.  Some service providers offer multi-tiered contract programs (e.g. Platinum, Gold and Silver) with dedicated support line reserved for the premium customers. 

Choosing the Right Service Provider to Service Your Industrial X-ray System

Selecting a service provider that can best serve an end user’s preventive maintenance needs goes much beyond pricing and service offering option considerations.  While no production managers can 100% prevent equipment failures and errors from having a direct negative impact to their production operations, they can still have the peace of mind knowing that there is always someone within reach to help address the issues whenever problems arise.  How fast, and how effective a solution can be provided are much more critical during production crisis. 

Other factors to consider when selecting the service provider that can best serve the preventive maintenance needs include the consistency of the skill and experience of the technicians of the service organization; access to factory support related to major X-ray components such as tubes and detectors; 3rd party referral and reference on whether the provider stands behind their service; and last but not least, their ability and expectation to help their customers identify and mitigate risks and potential issues.  After all, the goal of preventive maintenance service is to minimize or prevent potential downtime that can be caused by equipment failures.

The True Value of Preventive Maintenance

Having a preventive maintenance plan for the industrial X-ray system is a proactive cost-containment strategy for companies and organization of all sizes.  It isn’t just about the ensuring the equipment running at peak performance. It is about reducing the likelihood of expensive emergency equipment repair service or premature replacements.  It is also about enabling the X-ray equipment operator to perform his or her duties at an optimum level, with the insurance that for any problems that may happen, will be handled by the right expert, at the right time!

 

Reference
Digital Radiography: Description and User’s Guide

DIR 2007 - International Symposium on Digital industrial Radiology and Computed Tomography, June 25-27, 2007, Lyon, France


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