Meisterprüfung Metalltechnik flashcards

35 cards. Read the term and the definition here. The deck at the top of this page is optional.

0.2 % offset yield strength

Stress at which the plastic strain reaches 0.2 percent of the gauge length, determined from the tensile test per DIN EN ISO 6892-1, used for steels without a distinct yield point.

Carbon equivalent CEV

Formula CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Cu+Ni)/15 estimating weldability. Values above roughly 0.45 indicate cold-cracking risk and require preheating and controlled cooling.

Jominy end-quench test

Standard hardenability test in which a heated cylindrical specimen is quenched by a water jet at one end; hardness measured along the length shows how deeply the steel hardens.

Heat input in welding

Energy per unit length Q = k · U · I / v, with k about 0.8 to 0.9 for MAG welding. It controls cooling time, hardness and toughness of the heat-affected zone.

ISO 286 fit system

Tolerance system with hole-basis or shaft-basis fits. Letter gives the fundamental deviation, the number the IT grade; H/h are the basic holes and shafts.

Surface roughness Ra and Rz

Ra is the arithmetic mean roughness value of the profile, Rz the mean peak-to-valley height of five single measurements. Ra is roughly Rz divided by four to six.

Cutting speed formula

vc = π · d · n / 1000 in m/min with diameter d in millimetres and speed n in revolutions per minute; rearranged it gives the required spindle speed.

Hooke's law in engineering

In the elastic range stress equals modulus times strain, σ = E · ε. Young's modulus is about 210 GPa for steel and about 70 GPa for aluminium alloys.

Thermal expansion calculation

Length change Δl = l0 · α · ΔT. Steel expands about 11 to 13 · 10⁻⁶ per kelvin, aluminium about 23 · 10⁻⁶, which explains distortion during welding.

First-angle projection

Drawing arrangement used in Europe per ISO 128: the view seen from the left is placed on the right of the front view, and the top view is placed below.

Fully constrained CAD sketch

A sketch whose geometry is fixed by dimensions and geometric constraints so that no degrees of freedom remain; changes then propagate predictably through the parametric model.

Machine-hour rate

Cost per machine hour, calculated from depreciation, space, energy, maintenance, imputed interest and wages divided by the planned annual machine hours of that workstation.

Break-even quantity

Number of units at which revenue equals total cost, calculated as fixed costs divided by the contribution margin per unit, which is price minus variable cost per unit.

Linear depreciation

Annual depreciation equals acquisition cost minus residual value, divided by useful life. It spreads the loss in value evenly over the years of use of the asset.

Contribution margin ratio

Contribution margin per unit divided by selling price, expressed as a percentage. It shows how much of each euro of revenue remains to cover fixed costs.

Discount cost calculation

Skipping a discount has an annualised cost: discount rate divided by 100 minus discount rate, multiplied by 360 divided by the difference between payment and discount periods.

Werkvertrag under German law

Contract for work and services under the BGB in which the contractor owes a specific result; warranty for works and buildings is two years, for buildings five years.

Handwerksordnung Annex A

List of craft trades for which entry in the Handwerksrolle requires a master craftsperson qualification or an equivalent recognised qualification; metalworking trades such as metalworker belong here.

Working time breaks

German Working Time Act: 30 minutes break after more than six hours, 45 minutes after more than nine hours; at least 11 hours rest between shifts.

Product liability period

Under the German Product Liability Act the manufacturer is strictly liable for defective products for ten years after placing the product on the market; development risks are excluded.

Four-step training method

Instruction sequence: prepare and motivate, demonstrate and explain, let the trainee imitate and practise with correction, then consolidate through independent practice and transfer.

Operational training plan

Company plan derived from the framework training plan, allocating the required skills, contents and time slots of the apprenticeship to departments and training years.

Bloom's taxonomy levels

Ordered cognitive levels from remember, understand, apply, analyse and evaluate to create, used to formulate learning objectives and to design examination tasks of increasing difficulty.

Training record duty

Apprentices must keep a written or electronic record of their training; the trainer checks it regularly, and it serves as evidence of the training content covered.

STOP principle

Order of safety measures: substitution, then technical, then organisational, then personal protective measures. Personal protective equipment is the last barrier, never the first choice.

Noise action levels

At 80 dB(A) the employer must provide hearing protection and information; at 85 dB(A) hearing protection must be worn and audiometric testing is required.

Five safety rules electrical

Disconnect, secure against reconnection, verify absence of voltage, earth and short-circuit, and cover or bar adjacent live parts before working on electrical equipment.

Fire class D

Fire class for burning metals such as magnesium, sodium or aluminium powder. It requires special dry powder extinguishing agents; water and carbon dioxide are dangerous here.

Waste hierarchy

Order of waste handling under the German Circular Economy Act: avoidance first, then reuse, then recycling, then other recovery such as energy, and disposal only as the last option.

Coolant monitoring

Water-mixed metalworking fluids must be checked regularly for concentration, pH value, microbial contamination and nitrite; disposal requires separating oil from water.

Compressed air leakage cost

A small leak of about three millimetres at six bar wastes several thousand kilowatt-hours per year, so leak detection and pressure reduction are primary efficiency measures.

Critical path in projects

The longest chain of dependent activities that determines the minimum project duration; any delay on this path delays the whole project unless measures are taken.

Cost performance index

Earned value divided by actual cost. A value below one shows that the project has spent more than the work performed is worth, indicating a cost overrun.

Risk matrix

Tool ranking risks by multiplying probability of occurrence and impact of damage; high-scoring risks need prioritised measures with a named owner and a review date.

Acceptance protocol

Document recording measurable acceptance criteria, test results, deviations found and their correction, signed by client and contractor to close the project formally.