Define a profile and process

PyExtrusion deliberately separates the profile from the process conditions.

Profile

A Profile describes the section being extruded.

from pyextrusion import Profile

profile = Profile(
    linear_weight_kg_m=1.35,
    exits=2,
    profile_type="solid",
)

Required profile information

• linear_weight_kg_m: linear weight of one exit, in kg/m;
• exits: number of die exits;
• profile_type: physical family of the profile.

Supported profile types

User value	Meaning	Internal family
solid	Solid profile	solid
plate	Plate / flat solid	solid
hollow	Hollow profile	hollow
tubular	Tube / tubular profile	hollow

The profile type is required. PyExtrusion does not guess it.

Exits are strict integers

Valid:

1
2
3
4

Invalid:

2.5
"2"
True

Process

A Process describes how the profile is extruded, not how much will be produced.

from pyextrusion import Process

process = Process(
    exit_speed_m_min=24,
    cut_length_mm=7000,
    trim_total_per_billet_m=2,
    complexity="normal",
)

Main process inputs

• exit/profile speed;
• cut length;
• total trim/reject reserve per incoming billet (trim_total_per_billet_m);
• complexity;
• optional manual number of cuts;
• optional butt override (butt_mm: physical residual thickness inside the container);
• explicit legacy front-scrap inputs for older data only; do not combine with canonical trim.

For p sequential pulls, trim_per_contribution = trim_total_per_billet_m / p. This total is not front-only scrap, trim per pull or a metallurgical charge-weld prediction. The output trim_per_pull_m sums all contributions in a full pull; it is not always the per-contribution value.

See trim topology and legacy migration. In particular, a synthetic legacy front_scrap_m=0.6 with two sequential pulls becomes canonical total 1.2, not 0.6.

The butt input and plant butt rules retain physical mm values. Defaults remain 15 mm for solid/plate and 20 mm for hollow/tubular. No numeric input migration is required. Butt mass uses density and the container-bore section. The engine converts this mass to an equivalent incoming-billet length internally, once. billet_kg_per_mm_override changes the incoming-billet coefficient and upstream billet-saw loss, not that physical butt mass. The v0.18.0 correction can change calculated lengths, losses and discrete feasibility compared with earlier calculations, which used the incoming-billet section for the butt.

Important process ranges

Input	Supported range / rule
Cut length	1000 to 15000 mm
Exit/profile speed	1 to 100 m/min
Total trim per billet	Finite and nonnegative; geometry is checked after distribution across pulls
Complexity	normal, medium, high

PyExtrusion never guesses units. For example:

cut_length_mm=7

means 7 mm, not 7 m, and is rejected.

Enter ram speed instead of exit speed

If your plant works naturally with ram speed, you can provide it as the speed input:

process = Process.from_ram_speed(
    ram_speed_mm_s=0.70,
    cut_length_mm=7000,
    trim_total_per_billet_m=2,
    complexity="normal",
)

PyExtrusion then derives the corresponding profile exit speed from the press/profile geometry.

Do not supply both ram speed and exit speed for the same process. They are alternative inputs.

Build a PlanningCase

from pyextrusion import PlanningCase

case = PlanningCase(
    profile=profile,
    process=process,
)

This object contains no production quantity. The same PlanningCase can therefore be reused for 300 bars, 20 billets, 2500 kg or a two-hour capacity check.

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