Glossary of extrusion and PyExtrusion terms¶
This glossary is intended for readers who are new to aluminium extrusion or to the terminology used by PyExtrusion.
Aluminium extrusion¶
A manufacturing process in which heated aluminium is forced through a die opening to create a long product with a constant cross-section.
Bar¶
A finished cut length of extruded profile. In PyExtrusion, a request such as PlanningRequest.bars(300) means 300 finished cut lengths.
Billet¶
A cylindrical piece of aluminium loaded into the extrusion press as raw material. PyExtrusion normally works with whole billets, not fractions of a billet.
Billet diameter¶
The actual outside diameter of the billet before it is upset inside the container.
Billet length¶
The length of billet required or used for a calculated process. PyExtrusion may report both a mathematical value and a recommended whole-millimetre value.
Billet-on-billet / multi-billet continuous pull¶
A production situation in which material from successive billets contributes to one continuous extrusion pull. In PyExtrusion this is represented by the generic configuration k_billets_1_profile.
Billets per pull¶
The number of billets contributing to one continuous pull. This can be 1 or more depending on the process and table geometry.
Butt / butt discard¶
The residual aluminium left in the filled container at the end of the stroke and discarded. butt_mm measures its physical thickness in front of the dummy block. Its mass uses the container section, not the incoming-billet section.
Equivalent butt length¶
The incoming-billet length representing the butt mass: butt_mass_kg / effective_billet_kg_per_mm. This differs from physical butt_mm when billet and container sections differ. Do not replace an existing physical 15, 20, 25, 30 or 35 mm input by this equivalent length.
Complexity¶
A PyExtrusion process input used to represent a practical allowance for additional process losses. Public values are normal, medium and high.
Container¶
The cylindrical press component that surrounds and supports the billet during direct extrusion.
Container bore¶
The inside diameter of the container. Do not confuse it with the billet diameter: they are related but not identical.
Cut¶
One finished-length division along the extruded pull. In PyExtrusion, cuts counts commercial positions per billet contribution to one pull and per exit, not all physical saw strokes. A p=2 billet contributes that count twice.
Cut length¶
The target finished bar length entered in millimetres. Example: a seven-metre bar is entered as 7000 mm.
Dead time¶
A technical non-extruding time included in the current press-time model between relevant billet/process events. It is not the same as plant waiting time between production orders.
Die¶
The tooling containing the opening(s) through which aluminium flows to create the profile cross-section.
Direct extrusion¶
An extrusion process in which the ram pushes the billet through a stationary die in the same general direction as the ram movement. This is the process family currently modeled by PyExtrusion.
Exit¶
One die opening producing one strand/profile at the same time. A die with two exits produces two simultaneous strands.
Exit speed / extrusion speed¶
The linear speed of the extruded profile leaving the die, expressed by PyExtrusion in metres per minute.
Extrusion ratio (RE)¶
A ratio describing the reduction from the incoming container cross-section to the total outgoing extrusion cross-section. It is an important process indicator, but it should not be used alone to accept or reject a production route.
Fixed scrap¶
A PyExtrusion summary group containing fixed process losses such as physical butt, total trim and saw-related losses.
F_baseline¶
Equivalent-axisymmetric mechanical force baseline calculated from peak pressure and container-bore area. It is not the final load prediction for a real shaped, bridge or porthole die.
F_reserve¶
Arithmetic screening difference F_press - F_baseline. It is not guaranteed
remaining capacity, available hydraulic capacity, a safety margin or force available for a porthole die.
Total trim / reject reserve and legacy front scrap¶
trim_total_per_billet_m is total rejected length per incoming billet, split across sequential pulls and distributed around each commercial block. It is not only leading crop and is not predicted charge-weld length. Legacy front_scrap_m remains per billet for p=1 and per pull for p=2. See trim topology.
Commercial positions and physical saw events¶
cuts and cuts_per_pull count commercial positions per exit. The separate production.final_saw_events counts transverse saw strokes across all exits; internal_billet_transitions, puller_saw_events and billet_saw_events have separate physical meanings.
Trim per contribution / trim per full pull¶
One incoming billet's total reserve is divided by profiles_per_billet to obtain trim per contribution. The result trim_per_pull_m sums the contributions of a complete pull. For a partial last pull, use only its actual billets; do not treat a full-pull result as the partial total.
Internal billet transition¶
A boundary between successive billets inside the same continuous pull. For p=1, the actual order count is billets minus pulls; for p=2 it is zero. With positive trim, the corresponding rejected zones affect final-saw topology. A transition is not another puller or press dead-time event.
Good kg¶
Mass of finished product considered acceptable/output material, excluding the process-loss categories represented by the calculation.
Gross productivity¶
Production rate before focusing only on good finished output. PyExtrusion distinguishes nominal and real gross productivity.
Hollow profile¶
A profile containing one or more enclosed internal voids. Use profile_type="hollow".
Kerf¶
The width of material removed by a saw cut. PyExtrusion can model billet, puller and final-saw kerfs separately. A zero kerf removes its represented length/mass loss, not the declared physical event.
Linear weight¶
Mass per unit length of one profile strand, normally expressed in kg/m. In PyExtrusion, linear_weight_kg_m is the linear weight of one exit.
Net productivity¶
Good manufactured mass divided by the technical press time represented by the calculation. It is commonly expressed in kg/h.
Nominal press size¶
The conventional inch size used to identify a press/billet class, such as 8-inch or 9-inch. In PyExtrusion the currently supported nominal range is 6 to 16 inches.
PlanningCase¶
A PyExtrusion object combining a Profile and a Process. It describes a production method without specifying the required quantity.
PlanningRequest¶
The quantity or capacity question applied to a PlanningCase, for example:
- 300 bars;
- 2500 kg;
- 1800 m;
- 20 billets;
- 2 hours available.
Plate¶
A flat/solid profile family accepted with profile_type="plate". PyExtrusion treats it within the solid family for calculation purposes.
Press¶
The extrusion machine and its relevant limits/configuration as represented by the PyExtrusion Press object.
Process / ProcessSpec¶
The PyExtrusion object describing how a profile is extruded: speed, cut length, total trim per incoming billet, complexity and optional process overrides. It does not contain the order quantity.
Production order¶
A user-defined order identifier plus a PlanningCase and a quantity-based PlanningRequest, represented by ProductionOrder in sequence calculations.
Production sequence¶
An ordered list of production orders calculated one after another. PyExtrusion preserves the list order and accumulates technical press time only.
Productivity index¶
An orientative PyExtrusion utilisation indicator combining several aspects of the calculated process. It is not a physical quantity and must not be used alone to choose a press.
Profile¶
The extruded product cross-section. In PyExtrusion, a profile is mainly described by linear weight, number of exits, profile type and optionally an explicit section.
Profiles per billet¶
The number of complete sequential profiles/pulls produced by one billet in the selected configuration. The current PyExtrusion model supports a maximum of two.
Pull¶
A continuous length of extrusion handled on the press/runout table as one extrusion pull. One pull can contain the contribution of more than one billet.
Puller¶
Equipment that grips/guides the extruded profile as it leaves the press and travels along the runout table.
Puller saw¶
A saw operation associated with the end of each actual pull. production.puller_saw_events counts the operations; zero kerf gives zero loss without removing these events.
Ram¶
The moving press component that applies force through the stem/dummy block to push the billet through the die.
Ram speed¶
The forward speed of the press ram, commonly represented by PyExtrusion in mm/s. It is much lower than profile exit speed because the outgoing material cross-section is much smaller than the container cross-section.
Recommended billet length¶
A practical billet-length suggestion returned by PyExtrusion, rounded upward to a whole millimetre from the mathematical calculated value.
Runout table / table¶
The length available after the press for the extrusion pull. In PyExtrusion, table_length_m is mandatory because it strongly influences feasible pull geometry.
Scrap / process loss¶
Material represented by the calculation as not becoming good finished product. PyExtrusion separates several loss categories so they can be inspected individually.
Solid profile¶
A profile without an enclosed internal void. Use profile_type="solid".
Supported¶
A PyExtrusion status meaning the scenario is covered by the current approved calculation model. supported=False means the current model intentionally does not calculate that configuration.
Table occupancy¶
The amount of runout-table length occupied by the calculated recommended pull configuration.
Target productivity¶
A reference net productivity used for comparison/interpretation. A real plant target supplied by the user should be preferred when available.
Theoretical start/end time¶
Clock timestamps obtained when a sequence is given a start_at value. They assume continuous technical press time and do not include unmodeled plant delays.
Tubular profile¶
A tube-type profile accepted with profile_type="tubular". PyExtrusion treats it within the hollow family for calculation purposes.
Viable¶
A PyExtrusion status meaning a supported scenario has at least one process configuration that fits the current press/process constraints.
Warning¶
A message drawing attention to an unusual, weak or potentially unfavorable calculated condition. Warnings support engineering review; they do not replace it.