Advanced Material Removal Processes & Quality Management

Posted on Jan 22, 2025 in Business Administration and Innovation Management

Advanced Material Removal Processes

Conventional Machining: Material removal through mechanical processes.

Electro-Discharge Machining (EDM): Material removal by controlled electrical discharges. Part of the electrode-discharge occurs within a dielectric fluid, causing erosion.

Benefits: Suitable for hard and refractory materials, complex geometries.

Disadvantages: Requires specialized drivers, slow speed, can modify the material’s microstructure.

Dielectric Types: Penetrating (oil) and non-penetrating (deionized H2O).

Process: Electrical corrosion, voltage breakdown, temperature increase, ionization, and avalanche effect. Three affected zones: vaporized, melted, and heat-affected. Implosion of bubbles eliminates dielectric material.

Characteristics: Better thermal conductivity of the electrode (less wear), dielectric renewal, isotropic roughness. Qv = (Volume of Electrode / Volume of Piece) * 100.

Equipment: Bed, table, dielectric tank, filtration unit, head positioning, and impulse generator.

Functional Voltage (Vfunc) = f(GAP). Three Parameters: 1) ti (pulse on-time), 2) Intensity, 3) t0 (pulse off-time). Variations in their optimal values are crucial.

Ultrasonic Machining: Utilizes magnetostrictive or piezoelectric materials to amplify micro-oscillations (0.01 mm). Requires abrasive blasting. Suitable for various materials.

Electrochemical Machining (ECM): Electrolysis process. Part and tool are conductors immersed in an electrolyte (H2O + NaCl). Four functions: cleaning, cooling, and electrolyte flow. No physical contact.

Parameters: High voltage, high current, slow process. Electrolyte jet pumped from inside the tool.

Benefits: Works on hard materials, simultaneous machining, suitable for large series, high precision, good finish, no deformation.

Disadvantages: Setup complexity, corrosion, pump costs, side cuts (insulation needed).

Applications: Profile drilling, polishing, electrolytic rectification.

Chemical Milling: Uses an etching bath with protective polymers. Etching time (t) is a function of density and size. Successive immersions allow for complex geometries. Attack factor = Width / Depth > 1 (10 k). Inhibitors are used to control the process.

Disadvantages: Time-consuming and potential for hydrogen fragility.

Electrolytic Molding: Plating process to create thin shapes using a mold. Time (t) is a function of current and time. Nickel (hardness) and copper (precision) are common materials.

Applications: Missiles and jets.

Electron Beam Machining: Uses accelerated electrons guided by a magnetic field in a vacuum. Can cause blurring. Used for surface treatments and welding.

Applications: Precision drilling, suitable for various materials.

Laser Machining: Similar to electron beam but uses photons. Precise, suitable for surface treatments and welding. No vacuum required. Can be used for cutting and drilling.

Comprehensive Quality Plan

A structured approach defining responsibilities, activities, and resources to ensure products, processes, or services meet quality requirements.

Quality System Elements:

  1. Organization: Clearly defined responsibilities.
  2. Project and Product Launch: Measurement principles to ensure customer satisfaction.
  3. Purchases and Suppliers: Processes to ensure suppliers meet requirements.
  4. Manufacturing: Meeting specifications through fabrication and control plans.
  5. Quality Control: Ensuring the quality system functions effectively.
  6. Handling, Storage, and Transportation: Proper procedures to maintain product integrity.
  7. Assistance and Customer Service: Providing sufficient information for product use and support.
  8. Other: Material testing, analysis of returns, and complaint management.

Quality Manual: A document outlining all rules and procedures followed to ensure quality. The Quality Policy serves as the starting point.

Quality Costs: 1) Prevention, 2) Assessment, 3) Failure (internal and external).

Concept of Quality:

ISO Definition: A set of characteristics that enable an entity to meet established and implied needs.

UNE Definition: The degree to which a set of inherent characteristics fulfills requirements.

Quality is achieved through: Clear specifications, scrupulous execution, well-considered project, appropriate manufacturing process, proper packaging and transport, and good after-sales service.

Competitive Firm Levels:

  1. Minimum level.
  2. Competitive level.
  3. Above level: Technological innovation with no competition.

Evolution of Quality Management:

  1. Inspection (1930s): Ensuring quality by selecting and correcting defects.
  2. Process Control (1940s): Reducing dispersion by acting before problems arise.
  3. Integrated Quality Control (1960s).
  4. Total Quality: Considering all enterprise activities, shared responsibility, human factors (training, motivation), participation, information, communication, and prevention over correction. Includes internal customer focus.