Weld Evaluation Of Camshafts Using Ultrasonic Testing

Generally, ultrasonic testing (UT) is used to figure out the quality of brazed joints. With the help of this unique process, evaluating brazing quality becomes simple. It uses a focused transducer, and ultrasonic waves along the radius of the shaft are focused on the brazed joint. By monitoring the amplitude of the echoes returning from the joint position, one can evaluate the brazing quality easily.

When the echo becomes weak, it indicates a strong bond where most of the ultrasonic waves travel through the joint. On the other hand, a strong echo means that there is no mechanical bonding, causing the ultrasonic waves to bounce back at the interface. A reference sample with a known unbonded area can be used to set the ultrasonic machine sensitivity and evaluate the amount or percentage of any flaw in the part.

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Camshafts

Camshafts are typically manufactured by machining cast iron, forged steel or billets down to the desired shape. Some manufacturers have started to produce camshafts by joining cams to shafts with a brazed joint. Due to the force being potentially applied to the brazed joint, quality control is required to ensure brazing quality and that a sufficient percentage of cam is solidly brazed to the shaft. Ultrasonic testing must be conducted only through experts who provide certified non destructive testing in Melbourne.

Camshaft geometry

A camshaft is basically a shaft with cams distributed along its length. Cams can come in different shapes with one common characteristic: there is at least one protuberance found along the circumference, resulting in an irregular shape. A common model is a cam with a nose (lobe), where the brazed joint is not parallel to the outer surface. In such a situation, there is little to no probability of recording an echo from the joint; this is what will be referred to as the uninspectable area of a cam.

Brazed joint evaluation

It is not always necessary to inspect each individual part of the camshaft to control the quality of a production. A statistical analysis can be performed on sampled parts taken from the production line. The same logic applies to the uninspectable area of the cams; a statistical analysis can still be performed by monitoring the percentage of good brazing within the inspectable portion of the cams. When using ultrasounds to monitor the brazed joint quality, the evaluation must be normalized to ratio of inspectable area.

As ultrasonic testing is sensitive to both surface and sub-surface discontinuities, be sure to hire the certified personnel to figure out the flaws properly and end on a positive note.

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What Do You Understand By Coating?

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In the realm of welding and corrosion, coating can be defined as the sparse layers of any covering substance applied or deposited on the surface of an object, primarily for enhancing its properties. It also helps in forming a protective barrier to prevent the surface from deteriorating because of reaction with the external environment.

The surface onto which any coating is added, is known as a substrate. And the layers of protection keep it from undergoing electrochemical reactions with elements in the open atmosphere. As such, coating aids in ensuring good quality as well as increasing the lifespan of pipelines, structures and other important equipment. It even removes some critical and life threatening flaws, thereby saving millions in terms of financial resources pertinent to premature replacements and repairs.

According to experts offering the service of coating inspection in Melbourne, corrosion coating is usually:

  • A thin layer of some metal
  • Inorganic lining such as that of porcelain and glass
  • Organic coating like paint, varnish, polymeric materials, etc
  • Printed or etched covering or optical film layer

A typical coating might be applied for providing:

  • Resistance against scratches and abrasions
  • Protection from extremely high temperatures as well as fires
  • Wettability and capacity to seal
  • Insulation against the flow of static electric charge
  • Enhanced aesthetics and physical appearance
  • Resistance against corrosion
  • Non-stick or release property
  • Safety from cavitation, erosion, pitting and general wear & tear

Let’s take a look at some fine instances of coating in order to comprehend it better:

  • Components of jet engine covered with cermet
  • Fabrics provided with waterproof lining
  • Components having extrusion coating
  • Layers of anti corrosion and anti rust paint
  • Adhesive tapes
  • Varnish and polymeric material applied on pipelines & structures

There are a wide range of materials out there which act as substrates for coating. The most common ones include steel, various non-metals as well as other metals, paper, wood, plastics and fabric. In the modern times, coatings serve a primary purpose of offering protection to structures & pipes that are either buried deep into the ground or immersed under the surface of water, such as oil platforms & rigs.

In Melbourne, coating inspection is generally carried out by qualified coating inspectors in order to ensure the standard quality necessary for compliance with environmental, safety, operational and economic issues. The inspections are carried out with strong emphasis on industry standards, training and practices. Comprehensive downtime for re-coating and repairs are extensively minimised during these procedures.