Interview Questions for Brazing Inspection and Testing

Brazing is a joining process that uses a filler metal with a lower melting point than the base metals being joined. The key difference from welding is that brazing doesn’t melt the base materials; instead, it relies on capillary action to draw the molten filler metal into the joint.

Several brazing processes exist, differing primarily in how heat is applied:

• Torch Brazing: A common method using a gas torch to locally heat the joint. This offers flexibility for various joint geometries but requires skilled operators to control heat input precisely.
• Furnace Brazing: Parts are placed in a furnace with a controlled atmosphere for even heating. This is efficient for high-volume production but less adaptable to complex geometries.
• Induction Brazing: An electromagnetic field heats the workpiece, offering excellent control and repeatability, particularly useful for automated systems.
• Resistance Brazing: Electrical resistance heats the joint directly. Simple and effective for specific applications, but joint design needs to be carefully considered to ensure uniform heating.
• Dip Brazing: The assembly is immersed in a molten bath of filler metal. This is a fast and efficient method, suitable for mass production but limits the complexity of the joint design.

The choice of brazing process depends on factors like production volume, joint design, material properties, and required joint strength.

Inspecting brazed joints is crucial to ensure structural integrity and prevent failures. Various methods are employed, often in combination:

• Visual Inspection: The simplest method, involving careful examination of the joint’s surface for visible defects. This is often the first step and can reveal major problems.
• Liquid Penetrant Testing (LPT): A non-destructive test that detects surface-breaking defects like cracks and porosity. A dye is applied, drawn into the defect, and then revealed using a developer.
• Dye Penetrant Testing: Similar to LPT but using fluorescent dyes that are more sensitive and easier to detect under UV light. Especially useful for intricate joints.
• Radiographic Testing (RT): X-rays or gamma rays are used to detect internal flaws like porosity, cracks, and incomplete penetration. This is a more sophisticated and expensive method.
• Ultrasonic Testing (UT): High-frequency sound waves are used to detect internal defects and measure joint thickness. This method provides precise information about the internal structure of the brazed joint.
• Leak Testing: Essential for brazed joints in pressure systems or applications where leaks cannot be tolerated. Methods include pressure testing, vacuum testing, or helium leak detection.

The choice of inspection method depends on the criticality of the application, the complexity of the joint, and the required level of sensitivity.

Several defects can occur during brazing, compromising the joint’s strength and reliability. Common defects include:

• Porosity: Gas bubbles trapped in the filler metal, weakening the joint and potentially leading to leaks.
• Incomplete Penetration: The filler metal doesn’t fully penetrate between the base materials, resulting in a weak and unreliable joint.
• Cracks: These can form in the filler metal or the base material due to stress or improper brazing parameters.
• Burn-through: Excessive heating melts or weakens the base materials.
• Insufficient Filler Metal: Not enough filler metal leads to incomplete joint formation.
• Intermetallic Compound Formation: Reaction between the filler metal and base materials may lead to brittle intermetallic compounds which reduce joint strength.
• Base Metal Contamination: Oxides or other contaminants on the base metal surfaces can prevent proper wetting and bonding.

Understanding these defects is crucial for effective quality control and process optimization.

Porosity in a brazed joint can be identified using several methods:

• Visual Inspection: While not always definitive, surface porosity might be visible as small pinholes or surface irregularities.
• Liquid Penetrant Testing (LPT): Surface-breaking porosity can be detected, allowing for the identification of pores that reach the surface of the braze joint.
• Radiographic Testing (RT): This provides the most reliable detection of both internal and surface porosity; the X-ray or gamma ray image will reveal the presence and extent of internal pores.
• Ultrasonic Testing (UT): This technique detects internal porosity by measuring the changes in sound wave reflections. UT can provide information about the size and distribution of the pores.

The selection of method depends on the access to the braze joint and the required sensitivity of the inspection.

Visual inspection is the simplest and often the first step in brazed joint examination. It involves a thorough visual examination of the joint’s surface under suitable lighting conditions. The principles are:

• Proper Lighting: Sufficient illumination is crucial to reveal surface defects. Magnification aids can improve the detectability of small imperfections.
• Joint Geometry Assessment: The shape and dimensions of the joint are checked to ensure they conform to specifications. Any irregularities could indicate problems.
• Surface Examination: The surface is inspected for cracks, porosity, incomplete penetration, excess filler metal, discoloration, and other visible anomalies.
• Documentation: All observations should be carefully documented, including photographic evidence.

Think of it like a careful visual ‘health check’ of the joint. While limitations exist, it’s a cost-effective and quick initial assessment.

Visual inspection, while simple and quick, has limitations:

• Limited Depth of Detection: Visual inspection can only detect surface flaws; internal defects are invisible.
• Subjectivity: Interpretation of findings can be subjective, requiring skilled and experienced inspectors to ensure consistency.
• Accessibility Issues: Inspecting complex or inaccessible joints can be difficult or impossible.
• Small Defect Detection: Visual inspection is not sensitive to very small defects that might still compromise the integrity of the braze joint.

Therefore, visual inspection should be considered a preliminary screening and complemented by other, more sensitive non-destructive testing methods for complete and reliable assessment.

Liquid Penetrant Testing (LPT) is a widely used non-destructive testing method for detecting surface-breaking defects in brazed joints. The procedure generally follows these steps:

1. Cleaning: The brazed joint surface is thoroughly cleaned to remove any dirt, grease, or other contaminants that might obstruct the penetrant.
2. Penetrant Application: A liquid penetrant is applied to the surface and allowed to dwell for a specified time, enabling the penetrant to seep into any surface-breaking defects.
3. Excess Penetrant Removal: After the dwell time, excess penetrant is carefully removed from the surface using a suitable method (e.g., wiping or washing).
4. Developer Application: A developer is applied to draw the penetrant out of the defects and make them visible. Developers can be wet or dry.
5. Inspection: The surface is inspected for indications (e.g., bleed-out of the penetrant from the defects). The use of magnification and suitable lighting is crucial here.
6. Interpretation and Documentation: The inspection results are interpreted based on the size, shape, and location of the indications, and these findings are documented.

This method is relatively simple, cost-effective, and highly sensitive for detecting surface flaws making it a valuable tool in brazing inspection.

Magnetic particle inspection (MPI) is a non-destructive testing (NDT) method used to detect surface and near-surface flaws in ferromagnetic materials. For brazed joints, MPI can reveal cracks, porosity, or incomplete fusion near the surface of the joint. The process involves magnetizing the component, applying ferromagnetic particles (dry or wet), and observing the accumulation of particles at flaw locations, indicating discontinuities that disrupt the magnetic field. Think of it like sprinkling iron filings on a magnet – the filings cluster around the poles, similarly, particles gather at defects.

Procedure:

• The brazed joint is magnetized using either a yoke (for localized inspection) or a coil (for larger areas).
• Ferromagnetic particles (usually finely powdered iron or iron oxide) are applied to the magnetized surface, either dry or suspended in a liquid carrier.
• The particles are drawn to areas of magnetic flux leakage caused by discontinuities, forming visible indications.
• The inspection is carried out under appropriate lighting conditions, often using black light for fluorescent particles, for enhanced visibility.
• The indications are evaluated based on their size, shape, and location to determine their significance.

Limitations: MPI is surface-sensitive and cannot detect internal flaws effectively. It also requires the component to be ferromagnetic.

Radiographic testing (RT), also known as X-ray or gamma-ray testing, is a powerful NDT method that uses penetrating radiation to create an image of the internal structure of a material. For brazed joints, RT can reveal internal flaws such as porosity, lack of fusion, cracks, and inclusions in the braze filler metal or the base materials.

Advantages:

• High sensitivity to internal flaws: RT can detect internal flaws that are invisible to surface inspection methods.
• Permanent record: Radiographic images provide a permanent record of the inspection.
• Wide applicability: RT can be used on a variety of materials and joint configurations.

Disadvantages:

• Safety concerns: RT involves ionizing radiation, requiring specialized training and safety precautions.
• Cost: RT equipment and expertise can be expensive.
• Limited access: RT might be difficult to perform on complex geometries or inaccessible areas.
• Interpretation complexity: Interpreting radiographic images requires specialized knowledge and experience. Subtle flaws might be missed.

Interpreting radiographic images of brazed joints requires experience and a thorough understanding of brazing processes and potential defects. Radiographers look for variations in density or changes in the image that indicate discontinuities. Darker areas (higher density) can represent areas of greater material thickness or density (such as base metal compared to braze material) while lighter areas (lower density) can indicate voids, porosity, or cracks. Think of it like looking at a shadow – the shape and darkness of the shadow reveals information about the underlying object.

Key aspects to look for:

• Lack of fusion: Appears as a dark line or discontinuity indicating incomplete bonding between the base metals and the filler metal.
• Porosity: Shows up as small, dark spots or irregular areas within the braze joint indicating gas pockets.
• Cracks: Appear as thin, dark lines, often extending from the braze metal into the base metal.
• Inclusions: Show as dark areas in the braze, representing trapped foreign material.

Radiographic interpretation is often supported by reference standards and comparison with known good joints. The interpretation must account for the thickness of the materials and the type of brazing process used. Any indication is carefully evaluated against the relevant acceptance criteria to determine acceptability.

Ultrasonic testing (UT) uses high-frequency sound waves to detect internal flaws in materials. For brazed joints, UT can identify flaws such as lack of fusion, cracks, porosity, and unbonded areas. It works by transmitting ultrasound into the material and analyzing the reflected signals (echoes). The echoes provide information about the material’s structure, revealing any abnormalities.

Procedure:

• A transducer is placed on the surface of the brazed joint.
• Ultrasound waves are transmitted into the material.
• The echoes reflected from interfaces (including flaws) are received by the transducer.
• A display shows the echoes as a function of time and amplitude, creating a waveform (A-scan) or an image (B-scan or C-scan) that reveals the presence and location of flaws.
• The type of transducer (contact or immersion) is selected depending on the geometry and accessibility of the joint.

Techniques: Common UT techniques employed for brazing inspection include pulse-echo and through-transmission methods. The choice depends on the geometry of the part and the type of discontinuities being sought.

Advantages: UT is highly sensitive to internal flaws and can be used on a variety of materials. It provides good depth penetration and has high resolution for flaw detection.

Acceptance criteria for brazed joints are specified in relevant codes and standards, such as AWS (American Welding Society), ASME (American Society of Mechanical Engineers), and ISO (International Organization for Standardization) standards. These criteria define the permissible levels of flaws in terms of size, type, and location. The specific criteria depend on the application, the material, and the design requirements. For example, a critical aerospace application will have much stricter criteria than a less demanding application.

Common acceptance criteria considerations:

• Maximum allowable flaw size: The largest acceptable flaw size (length, width, depth, or area) is defined.
• Number of allowable flaws: The maximum number of permissible flaws within a specified region might be limited.
• Flaw location: The location of the flaw can affect acceptance. Flaws in critical areas might result in rejection.
• Type of flaw: Different types of flaws (cracks, porosity, lack of fusion) might have different acceptance criteria.

Example: An AWS standard might specify that no cracks longer than 1mm are allowed in a particular type of brazed joint, and the total porosity should not exceed a certain percentage of the joint area. These criteria ensure the structural integrity and performance of the joint.

It’s crucial to consult and adhere to the specific codes and standards applicable to the specific project and application.

Selecting the appropriate brazing filler metal is crucial for achieving a sound and reliable brazed joint. The choice depends on several factors, including the base metals being joined, the desired joint properties (strength, ductility, corrosion resistance), and the brazing temperature.

Key factors to consider:

• Base metal compatibility: The filler metal must be compatible with the base metals to ensure proper wetting, flow, and bonding. The filler metal must have a lower melting point than the base metals.
• Joint strength and ductility: The filler metal should provide the required strength and ductility for the application. This may influence the choice of alloying elements.
• Corrosion resistance: If corrosion resistance is critical, a filler metal with appropriate corrosion-resistant properties should be selected.
• Brazing temperature: The filler metal’s melting point should be compatible with the brazing process and the temperature capability of the base materials.
• Application requirements: The specific requirements of the application, such as electrical conductivity, thermal conductivity, or specific mechanical properties, might dictate the choice of filler metal.

Selection process: Typically, manufacturers and engineers consult filler metal selection charts and datasheets to find a suitable filler metal based on the factors listed above. They often conduct trial brazes to confirm the compatibility and performance of the selected filler metal.

Joint design plays a vital role in achieving a successful brazed joint. A well-designed joint promotes uniform heat distribution during the brazing process, ensures proper capillary action of the filler metal, and minimizes the risk of defects. Think of it like building a strong bridge – the design must facilitate proper flow and support the structure’s weight.

Important aspects of joint design:

• Joint clearance: A proper clearance between the base metals is essential for the filler metal to flow freely into the joint. Too much clearance can result in excessive filler metal consumption, while too little clearance can prevent proper flow and lead to lack of fusion.
• Joint geometry: The shape and configuration of the joint affect the filler metal flow. Proper joint design promotes consistent wetting and bonding.
• Joint fit-up: Proper fit-up of the base materials is crucial for achieving a good braze joint. Any gaps or misalignments can hinder proper flow and cause defects.
• Heat transfer: The design should facilitate efficient heat transfer to the joint area to ensure consistent heating and melting of the filler metal.
• Stress considerations: The joint design must account for the stresses that will be placed on the joint during service to minimize the risk of joint failure.

A poorly designed joint can lead to a variety of problems such as incomplete penetration, porosity, cracks, and uneven filler metal distribution, compromising the strength and reliability of the final assembly. Careful consideration of these design aspects is critical to ensure a high-quality brazed joint.

The strength of a brazed joint hinges on several interconnected factors. Think of it like building a strong bridge – you need strong materials and a robust connection. Firstly, the base materials themselves are crucial; their compatibility with the brazing filler metal and their inherent strength directly impact the joint’s overall strength. Secondly, the filler metal’s properties are paramount. The right filler metal will have a melting point appropriate for the application, good flow characteristics to ensure complete filling of the joint, and sufficient tensile strength. Thirdly, the joint design plays a significant role. A well-designed joint with proper gap tolerances ensures good capillary action and avoids stress concentrations, leading to a stronger joint. Finally, the brazing process parameters, such as temperature, time, and atmosphere, significantly influence the final bond quality. Improper control can lead to weak or incomplete joints. For instance, insufficient heat may lead to incomplete melting of the filler metal, resulting in a porous and weak joint. Conversely, excessive heat can damage the base materials.

Controlling brazing process parameters is akin to baking a cake – precise measurements are key. We use a combination of techniques to achieve this. Precise temperature control is achieved using thermocouples or infrared thermometers to monitor the temperature profile throughout the brazing cycle. This ensures the filler metal melts and flows correctly without overheating the base materials. Time control is crucial; sufficient dwell time at the proper temperature allows for complete wetting and capillary action, creating a strong bond. Too little time results in incomplete brazing, while too much can cause excessive grain growth and reduce strength. Proper atmosphere control is essential to prevent oxidation or other detrimental reactions. A controlled atmosphere furnace or the use of a protective flux helps create the ideal environment for the brazing process. Finally, consistent joint preparation is a must; clean, uniform surfaces with proper gap tolerances ensure proper filler metal flow. Regular calibration and maintenance of equipment are essential to maintain process consistency.

Cleaning brazed components is critical for ensuring both the structural integrity and the cosmetic appearance of the joint. It’s like cleaning a wound before applying a bandage. The process usually begins with removing excess flux, which is often done using a suitable solvent or water-based cleaner, followed by thorough rinsing. Depending on the type of flux and the brazing material, specialized cleaning techniques may be necessary. Ultrasonic cleaning can be effective in removing embedded particles from complex geometries. Then, the components are often degreased to remove any residual oils or contaminants. This can involve the use of solvents or alkaline cleaners followed by rinsing and drying. After cleaning, inspection is vital to ensure that all flux and contaminants have been removed. For high-precision applications, additional steps such as chemical etching or electropolishing may be employed to achieve a superior surface finish.

Brazing and inspection involve several inherent safety risks requiring careful attention. Eye protection is paramount to prevent injury from flying debris or intense light. Safety glasses or face shields are always required. Respiratory protection is also essential, especially when working with fluxes or filler metals that produce fumes. Proper ventilation or the use of respirators is crucial. Heat-resistant gloves and clothing should be worn to prevent burns. Furthermore, appropriate fire safety precautions should be taken, especially when working with flammable materials or high temperatures. It’s also important to handle brazing filler metals carefully, avoiding contact with skin. During inspection, appropriate handling of inspection equipment is needed; some equipment operates at high voltages or uses hazardous chemicals. Safety data sheets (SDS) should always be consulted before commencing any operation.

Proper documentation and reporting of brazing inspection results are essential for traceability and quality control. This is crucial for ensuring the long-term reliability of the brazed components. Documentation typically involves creating a detailed inspection report that includes information such as the part number, date of inspection, inspector’s name, inspection methods used (visual, radiographic, etc.), and the results of the inspection. Photographs or video recordings can supplement written documentation, offering visual evidence of the brazing process and the quality of the joints. Any detected defects should be clearly documented, including their location, type, and size. The report must also include the acceptance criteria used to determine whether the brazed components meet the required standards. This detailed documentation allows for efficient tracing of components back to the specific brazing process, assisting in quality control and root-cause analysis in case of failures. Often, electronic databases or quality management systems (QMS) are used to manage this information, ensuring data integrity and accessibility.

Metallurgical examination plays a vital role in investigating brazing failures. It’s like performing an autopsy to determine the cause of death. By examining the microstructure of the brazed joint, we can pinpoint the root cause of a failure. Techniques such as optical microscopy allow us to assess the integrity of the joint, identify potential defects like incomplete penetration or porosity, and evaluate the quality of the metallurgical bond between the filler metal and the base materials. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) provides higher magnification and elemental analysis, enabling a precise characterization of the joint’s composition and microstructure, identifying potential intermetallic compounds or inclusions that might have contributed to the failure. Mechanical testing, such as tensile testing, can determine the joint’s strength and ductility, providing quantitative data to support the microscopic observations. The overall goal is to identify any deviations from acceptable metallurgical standards that may have compromised the joint’s strength or durability.

Brazing and soldering are both joining processes that use a filler metal to bond two or more materials, but they differ significantly in their operating temperatures and the type of filler metals used. Brazing uses a filler metal with a melting point above 450°C (842°F), typically joining materials through capillary action. The base materials remain solid throughout the process. Think of it as welding with a lower temperature filler metal. It results in a strong, durable joint suitable for high-stress applications. In contrast, soldering uses a filler metal with a melting point below 450°C (842°F). The filler metal melts and flows, but the base metals remain solid. It produces a mechanically weaker joint than brazing and is frequently used in electronics or applications where high strength isn’t critical. For example, brazing might be used to join pipes carrying high-pressure fluids, while soldering might be used to join electrical components.

Handling non-conforming brazed joints involves a systematic approach prioritizing safety and quality. First, the non-conforming joint is isolated and documented, including its location, the type of defect, and any associated information like part number or batch. This ensures traceability. Then, we determine the severity of the defect according to the relevant standards (like ASME Section IX or similar). Minor defects might be acceptable under certain criteria, while major defects necessitate corrective action. This could involve rework, repair, or scrapping the component, depending on the severity and the cost-benefit analysis. A thorough root cause analysis (RCA) is crucial to prevent future occurrences. This may involve inspecting the brazing process parameters, examining the filler metal, or assessing operator training. Finally, the corrective actions are documented, and the process is monitored to ensure effectiveness.

For example, if a joint shows incomplete penetration, depending on its location and the required strength, it might be repaired by re-brazing. If the defect indicates a larger systematic problem, however, the entire batch might be inspected, and process parameters adjusted before continuing.

Common causes of brazing defects are diverse and often interconnected. They can be broadly classified into three main categories: process-related, material-related, and operator-related issues.

• Process-related issues often involve incorrect temperature profiles, insufficient dwell time at the brazing temperature, improper joint design (e.g., insufficient clearance), or inadequate flux application. For example, insufficient heat can result in incomplete fusion, while uneven heating leads to variations in the braze joint thickness.
• Material-related issues can stem from using contaminated base materials or improper filler metal selection. Contamination can cause poor wetting and weak joints. Incompatibility of the filler metal with the base materials can also lead to defects. For instance, using a filler metal with an incorrect melting point for the base materials results in poor bonding.
• Operator-related issues include inadequate training, inconsistent process execution (e.g., variable flux application), or improper handling of the components during the brazing process. Poor joint preparation (e.g., insufficient cleaning) can also lead to defects. An example of an operator-related error would be forgetting to apply the flux or applying it unevenly resulting in an incomplete bond.

My experience encompasses a variety of brazing inspection equipment, including:

• Visual inspection tools: Microscopes (both optical and digital) for detailed examination of joint surfaces, identifying porosity, cracks, or incomplete penetration. Borescopes are particularly useful for inspecting internal joints.
• Non-destructive testing (NDT) techniques: I’m proficient in radiographic testing (RT) to detect internal flaws such as porosity and inclusions. Dye penetrant testing (PT) is used to reveal surface-breaking discontinuities. Ultrasonic testing (UT) offers another approach for internal flaw detection, providing detailed depth information.
• Specialized equipment: I have worked with automated optical inspection (AOI) systems for high-volume production, allowing for rapid and consistent inspection. Cross-sectional metallography (using microscopy of a polished and etched section) allows for detailed analysis of joint microstructure and intermetallic formation to evaluate the quality of the braze joint at a microscopic level.

I am also familiar with data acquisition systems used in conjunction with these techniques, allowing me to record and analyze inspection data for process improvement and traceability.

Industry standards and codes for brazing inspection are crucial for ensuring consistent quality and safety. The specific standards depend on the industry and the application, but some commonly referenced standards include:

• ASME Section IX: This standard covers welding and brazing qualifications, including procedures and personnel certification, providing guidelines on inspection and testing techniques.
• AWS B2.1: The American Welding Society standard for brazing provides specifications for brazing materials and processes.
• ISO 9606-1: This ISO standard covers qualification and certification of welders, and some of its principles can be applied to brazing operators as well.
• MIL-STD-1835: The military standard for brazing provides specific requirements for brazing in military applications.

Additionally, many industries have their own internal specifications that supplement these standards. Adherence to these codes ensures that brazed joints meet required performance standards and that inspection procedures are consistent and reliable.

Statistical Process Control (SPC) is a powerful tool for monitoring and improving the brazing process. It involves collecting data on key process parameters, such as temperature, time, pressure, and flux application, during brazing. This data is then analyzed using statistical methods to identify trends, variations, and potential sources of defects. Control charts (like X-bar and R charts) are commonly used to visually represent process variability and to monitor whether the process remains within established control limits.

By applying SPC, we can detect deviations from the desired process parameters early on, before they lead to significant defects. This allows for proactive adjustments to maintain a consistent and high-quality brazing process. For example, if the control chart indicates an upward trend in the rejection rate of brazed joints, this signals a need for a thorough investigation into the root cause and potential adjustments to the process.

Discovering a critical brazing defect late in the production process requires a swift and decisive response. The immediate priority is to contain the problem and prevent further defects. The affected components are quarantined immediately to prevent their incorporation into the final product. A thorough investigation is launched, including an assessment of the specific defect, the number of affected components, and the potential consequences of the failure. This might involve complete inspection of the remainder of the batch.

The next step is corrective action. This could range from rework or repair (if feasible and cost-effective), to scrapping the faulty components, to adjusting the brazing process to prevent recurrence. Depending on the severity and potential safety implications, regulatory authorities may need to be notified. Finally, a detailed report outlining the root cause analysis, corrective actions taken, and preventive measures implemented must be documented.

An example might be a crack discovered in a brazed joint of a critical component. Immediately the batch is held, a root cause investigation done, and the component might need to be replaced with a new one made following a revised process. The customer needs to be informed as well.

My experience with brazing filler metals includes a wide range of alloys, each with specific properties and applications. The choice of filler metal depends critically on the base materials being joined, the desired joint strength, operating temperature, and corrosion resistance.

• Silver-based alloys: These offer excellent flow characteristics, high strength, and good corrosion resistance. They are commonly used in electronics, heat exchangers, and other applications requiring high reliability and ductility. Silver-copper alloys are a prime example.
• Copper-based alloys: These are often selected for their high thermal conductivity and good strength. Applications include joining copper and copper alloys in refrigeration systems and plumbing.
• Nickel-based alloys: These are characterized by high strength and corrosion resistance at elevated temperatures, making them suitable for high-temperature applications such as aerospace components.
• Aluminum-based alloys: These are employed for joining aluminum and its alloys, frequently found in automotive and aerospace industries. However, aluminum brazing requires a higher level of expertise due to its oxidation characteristics.

In each case, thorough understanding of the filler metal’s properties, including its melting point, flow characteristics, and compatibility with the base materials, is crucial for selecting the appropriate filler metal for a specific application. It is important to adhere to the manufacturer’s recommendations.