A screw press only performs as well as the material fed into it. A typical seed preparation line places four stages ahead of the press: cleaning, shelling/dehulling, crushing (size reduction, only for larger seeds), and roasting.
First, a seed cleaning machine removes stones, soil, metal and stalks — contaminants that damage press internals and degrade oil quality. Next, a dehulling machine strips shells from crops such as peanuts and sunflower. A crusher then breaks large kernels into uniform pieces, and finally a seed roasting machine heat-conditions the material so oil flows freely under pressure.
Shelling matters because shells absorb oil during pressing and their abrasive fibre wears the press worm and barrel. Removing them raises recoverable yield and extends press life. Modern industry equipment typically achieves 95–98% shelling rates with 2–5% kernel breakage; a purpose-built peanut shelling machine reaches around 95% in a single pass.
Roasting works at the cellular level: heat denatures protein and creates pores in the seed cell walls, letting oil escape under far less pressure. The effect is dramatic — in published research, sesame oil yield improved from 33.5% to 62.6% with roasting. Sesame is typically roasted at approximately 170°C for about 15 minutes, while other seeds span roughly 90–260°C depending on crop and target flavour.
A small village or workshop setup can begin with just two machines: a cleaner and a roaster (plus a sheller if processing in-shell peanuts or sunflower). Material moves between stages by hand, keeping investment minimal while still capturing most of the yield benefit.
A full line for continuous production adds a vibrating screen for precise grading, screw or bucket conveyors between machines, and storage hoppers that buffer flow. The sizing rule is simple: every upstream machine should slightly out-pace the press. For peanuts, sheller models typically range from approximately 300–400 kg/h up to 800–1,000 kg/h, so you can match capacity to presses from workshop to plant scale.
Buying pre-press machines individually often creates bottlenecks — a roaster too small for the press, or a cleaner that lets fines through to the sheller. It is usually cheaper and faster to specify the whole seed preparation equipment chain together, sized around your target daily output and crop mix.
SinoOil Machinery has manufactured factory-direct seed preparation and oil pressing equipment since 2009, supplying mills in 80+ countries with ISO9001, CE and SGS certification. Send us your crop type and target capacity and our engineers will recommend a matched pre-press configuration: request a free line layout.
You can cold-press raw seed, but yields are significantly lower. Roasting denatures protein and opens pores in the cell walls so oil releases more easily — published research on sesame recorded oil yield rising from 33.5% to 62.6% after roasting. Most commercial mills treat a roaster as essential, not optional.
Yes, for two reasons: shells absorb oil during pressing, lowering your recoverable yield, and the abrasive shell fragments accelerate wear on the screw press worm and cage. A dedicated peanut shelling machine typically achieves around 95% single-pass shelling with kernel breakage of roughly 5% or less.
Approximately 8–13% moisture is ideal. Too dry and kernels shatter (high breakage); too wet and shelling efficiency drops. In dry winter conditions, a common trick is to spray about 10 kg of warm water per 50 kg of peanuts, cover with film for around 10 hours, then sun-dry for about 1 hour before shelling.
Match each upstream machine's throughput to your press's hourly intake, with roughly 10–20% headroom so the press never starves. For example, a press taking around 500 kg/h of peanut kernels pairs with a mid-size sheller (approximately 400–600 kg/h shelled output) and a roaster of matching capacity.
SinoOil engineers size the right pretreatment equipment for your capacity — free plant design included.
Get Engineering Support →