Lesson 1Dielectric fluids and flushing: types (deionized water, hydrocarbon dielectric), properties, contaminants, filtration basicsThis section examines dielectric fluids and flushing, comparing deionized water and hydrocarbon oils, their properties, contamination mechanisms, filtration basics, and flushing strategies that stabilize discharges and improve accuracy for reliable EDM operations.
Roles of the dielectric in EDM gapsDeionized water properties and controlHydrocarbon dielectric oils and safetyContaminants, sludge and aging effectsFiltration ratings and maintenance plansLesson 2Overview of EDM types: wire EDM vs sinker EDM, mechanisms, advantages and limitationsThis section compares wire and sinker EDM, explaining discharge mechanisms, tool–work interaction, and typical applications, then links these to advantages, limitations, and selection criteria for precision manufacturing tasks in Canadian industries.
Wire EDM kinematics and cutting path controlSinker EDM cavity machining and 3D formsSpark initiation, plasma channel and erosion cycleProcess advantages for hard materials and accuracyLimitations in speed, taper, and sharp cornersLesson 3Electrode and wire materials: copper, graphite, brass, tungsten; selection criteria and common diametersThis section analyzes electrode and wire materials such as copper, graphite, brass, and tungsten, discussing selection criteria, common diameters, wear behaviour, and how material choice affects speed, finish, and dimensional accuracy in EDM setups.
Copper electrodes for fine finishingGraphite electrodes for large cavitiesBrass and coated wires for wire EDMTungsten and copper-tungsten for detailCommon wire and electrode diametersLesson 4Standards and measurement tolerances: interpreting ±0.005 mm specs and Ra 0.4–0.8 µm requirementsThis section covers dimensional and surface standards relevant to EDM, interpreting ±0.005 mm tolerances and Ra 0.4–0.8 µm requirements, and explaining measurement methods, uncertainty, and documentation for inspection reports in Canadian practices.
Linear and geometric tolerance basicsReading ±0.005 mm on technical drawingsSpecifying and verifying Ra 0.4–0.8 µmContact and noncontact surface metrologyInspection reports and capability indicesLesson 5Material behaviour: hardened tool steel (approx. 58 HRC) response to EDM, recast layer, HAZ, microstructural effectsThis section examines how hardened tool steel near 58 HRC behaves under EDM, covering heat-affected and recast layers, microcracking risks, and microstructural changes that influence fatigue, wear, and dimensional stability in precision work.
Thermal cycles in 58 HRC tool steelFormation and composition of recast layerHeat-affected zone depth and gradientsMicrocracks, residual stress and fatigue lifeMicrostructural changes in martensitic steelsLesson 6Common machine features: servo control, gap sensing, automatic compensation, thermal compensation systemsThis section reviews common EDM machine features, including servo gap control, gap sensing, automatic wear and offset compensation, and thermal compensation, showing how they improve stability, accuracy, and unattended operation for Canadian shops.
Servo gap control principlesGap voltage and current sensing methodsAutomatic offset and wear compensationThermal compensation and drift controlMonitoring for stable unattended cuttingLesson 7Thermal damage and metallurgy control: recast depth, tempering, annealing strategies, reducing white layerThis section focuses on controlling thermal damage, including recast and white layer depth, tempering and annealing effects, and parameter and flushing strategies that minimize metallurgical degradation while preserving accuracy and life in EDM processes.
White layer formation and characterizationRecast depth versus energy and pulse shapeTempering and softening of hardened zonesAnnealing risks in thin or small featuresParameter tuning to reduce thermal damageLesson 8Surface finish and geometry capabilities: achievable Ra ranges, corner radius limits, tolerances and overcut fundamentalsThis section details EDM capability for geometry and finish, including typical Ra ranges, corner radius limits, overcut behaviour, and achievable tolerances, linking parameter choices and tooling strategy to functional dimensional accuracy.
Typical roughing and finishing Ra rangesCorner radius limits and wire diameter effectsOvercut definition, causes and controlAchievable tolerances in tool and die workStrategies for sharp edges and fine detailsLesson 9Electrical discharge theory: plasma channel, spark energy, pulse formation, material removal rateThis section explains the electrical discharge process, from field buildup and plasma channel formation to pulse energy, duty cycle, and material removal rate, relating circuit design and settings to erosion efficiency and stability in EDM theory.
Breakdown voltage and gap ionizationPlasma channel growth and collapsePulse current, on-time and off-time rolesEnergy per spark and crater formationMaterial removal rate models and limits
