Function of single-screw extruders

Sin­gle-screw extrud­ers are suit­able for pro­cess­ing homo­ge­neous, pure mate­ri­als. The poly­mer melts pri­mar­i­ly through fric­tion against the extrud­er wall. Through­put direct­ly depends on the screw speed — a high­er speed leads to more through­put. The qual­i­ty of the end prod­uct (e.g., melt­ing behav­ior, degree, and mix­ing effect) is sole­ly influ­enced by the design of the extrud­er screw and is there­fore only lim­it­ed­ly adjustable. While mix­ing process­es are fun­da­men­tal­ly pos­si­ble with a sin­gle-screw extrud­er, they are lim­it­ed and of low­er qual­i­ty.

How twin-screw extruders work

In con­trast, twin-screw extrud­ers are sig­nif­i­cant­ly more ver­sa­tile. Through­put is pri­mar­i­ly deter­mined by mate­r­i­al dos­ing, while the screw speed can be freely select­ed with­in a broad range. A high­er speed results in more ener­gy input, enhanc­ing the mix­ing effect and increas­ing the melt tem­per­a­ture. If a prod­uct requires par­tic­u­lar­ly gen­tle pro­cess­ing, this can be eas­i­ly achieved by reduc­ing the screw speed.

Func­tion­al­ly, twin-screw extrud­ers – so-called com­pounders — are ide­al for pro­cess­ing com­plex for­mu­la­tions, such as com­bin­ing dif­fer­ent mate­r­i­al streams (e.g., plas­tic, fillers, col­or mas­ter­batch). They are par­tic­u­lar­ly suit­able for demand­ing and high-qual­i­ty appli­ca­tions. While sin­gle-screw extrud­ers are designed for sim­ple, pure input frac­tions, twin-screw extrud­ers are often used when high­er qual­i­ty is required, such as in film pro­duc­tion, where the high­est demands on the puri­ty and homo­gene­ity of the gran­u­late must be met (e.g., avoid­ing gels in trans­par­ent films).

MAS extruders in the circular economy

In the cir­cu­lar econ­o­my, extru­sion is an essen­tial pro­cess­ing step: from the col­lect­ed end prod­uct (e.g., used pack­ag­ing), a high-qual­i­ty inter­me­di­ate prod­uct — the gran­u­late — is pro­duced.

Ini­tial­ly, the mate­r­i­al must be dried, as resid­ual mois­ture can neg­a­tive­ly affect the gran­u­late qual­i­ty. This is done either by pre-dry­ing before or by degassing dur­ing extru­sion. Since input mate­ri­als are often impure and con­t­a­m­i­nat­ed with for­eign sub­stances (such as alu­minum, wood, labels, straw, paper, or sand), sig­nif­i­cant tech­ni­cal effort is required to achieve a high-qual­i­ty end prod­uct. The removal of these con­t­a­m­i­nants is accom­plished through melt fil­ters.

An exam­ple of an effi­cient cir­cu­lar econ­o­my is the PET bot­tle: it is already pos­si­ble to pro­duce new food pack­ag­ing from used bot­tles (“bot­tle-to-bot­tle” recy­cling).

Why choose MAS?

At MAS, reduc­ing, reusing, and recy­cling are para­mount. Our extru­sion tech­nol­o­gy is designed for max­i­mum ener­gy effi­cien­cy and future via­bil­i­ty. This enables the con­tin­u­ous reuse of valu­able resources while reduc­ing the need for pri­ma­ry mate­ri­als. Our tech­no­log­i­cal­ly advanced and adapt­able extrud­ers and lines max­i­mize resource uti­liza­tion, reduce waste, and dri­ve sus­tain­able change through­out the recy­cling indus­try.

Cus­tomers ben­e­fit from indi­vid­u­al­ly tai­lored solu­tions that are high­ly eco­nom­i­cal and pay off quick­ly. Pre­cise adap­ta­tion to exist­ing sys­tems, rapid spare parts, and main­te­nance pack­age avail­abil­i­ty com­plete the offer­ing.

MAS twin-screw innovation at a glance

Com­pared to con­ven­tion­al, par­al­lel-run­ning twin-screw extrud­ers, MAS relies on its inno­v­a­tive con­i­cal co-rotat­ing tech­nol­o­gy, achiev­ing sig­nif­i­cant­ly stronger results on all lev­els:

• Large mate­r­i­al input: All mate­ri­als can be fed into the large feed open­ing, regard­less of bulk weight and com­po­si­tion. Even very light inputs, such as shred­ded PET bot­tles or PET films, are processed effort­less­ly with­out addi­tion­al side feed­ers and open­ings.
• Adjustable screw speed: Depend­ing on the input and desired out­put qual­i­ty, as well as any fillers or addi­tives, the screw speed can be freely defined. Slow, gen­tle pro­cess­ing and fast feed­ing with high homo­gene­ity are pos­si­ble while main­tain­ing con­sis­tent qual­i­ty.
• Short­er machine length: Con­ven­tion­al, par­al­lel-run­ning twin-screw extrud­ers often require mul­ti­ple feed open­ings and side feed­ers to con­tin­u­ous­ly adjust larg­er mate­r­i­al quan­ti­ties and addi­tives. The mate­r­i­al remains in the extrud­er at high­er tem­per­a­tures for longer, which can lead to degra­da­tion and qual­i­ty loss. Due to the large feed open­ing in MAS sys­tems, the entire twin-screw extrud­er is sig­nif­i­cant­ly more com­pact, result­ing in more con­sis­tent, high­er mate­r­i­al qual­i­ty, thanks to short­er res­i­dence times.
• Ener­gy effi­cien­cy: In addi­tion to the extend­ed length, con­ven­tion­al twin-screw extrud­ers must input sig­nif­i­cant­ly more ener­gy to process the mate­r­i­al through­out the entire dimen­sion and then remove it again, for exam­ple, as oil or water. MAS devices only require the ener­gy required to melt the plas­tic and need only a small fan for cool­ing. This also has a pos­i­tive effect on mate­r­i­al qual­i­ty.
• Opti­mal Re-com­pound­ing: Thanks to the flex­i­bil­i­ty in bulk weight and the high-pres­sure build-up due to the con­i­cal co-rotat­ing design, MAS twin-screw extrud­ers can more eas­i­ly intro­duce recy­cled mate­r­i­al and refine it with addi­tives and fillers. With con­sis­tent­ly high­er ener­gy effi­cien­cy, no addi­tion­al melt pumps or side feed­ers are need­ed.
• Reduced wear: Due to the mod­u­lar design of the screw, usu­al­ly only indi­vid­ual screw ele­ments need to be replaced. This reduces wear and leads to sig­nif­i­cant­ly longer dura­bil­i­ty of par­tic­u­lar com­po­nents. Due to the short­er machine length, less space is required for dis­as­sem­bly and replace­ment; the entire sys­tem does not need to be dis­man­tled first. This reduces pro­duc­tion inter­rup­tions (on aver­age, about half a day) and ensures faster sys­tem amor­ti­za­tion.

MAS twin-screw extruders in film applications

Due to their flex­i­bil­i­ty and strong prop­er­ties, MAS’s con­i­cal co-rotat­ing twin-screw extrud­ers are suit­able for var­i­ous plas­tics. In film recy­cling, qual­i­ty is para­mount. Con­ven­tion­al sin­gle-screw extrud­ers often leave small residues of recy­cled mate­r­i­al, known as “gels,” which can appear as dark col­or pig­ments (e.g., black specks in yel­low bag mate­ri­als). MAS sys­tems break these down entire­ly, pro­duc­ing uni­form, high-qual­i­ty films with­out defects, resem­bling new mate­r­i­al. Due to the short machine length and sig­nif­i­cant­ly short­er res­i­dence time in the twin-screw extrud­er, col­or val­ues can also be main­tained, mean­ing the mate­r­i­al does not degrade or yel­low. Addi­tion­al­ly, refine­ments with addi­tives and fillers are pos­si­ble at any time with­out issue.

MAS twin-screw extruders in PET applications

The exten­sive and high­ly flex­i­ble input of MAS sys­tems makes twin-screw extrud­ers the ide­al PET recy­cling solu­tion. All bulk mate­r­i­al com­bi­na­tions and mix­tures can be processed as desired. Even very light PET mate­ri­als can be processed more gen­tly and uni­form­ly thanks to reduced screw speed. The PET is direct­ly degassed dur­ing extru­sion and only trans­port­ed with­out unnec­es­sar­i­ly high tem­per­a­tures. This leads to less shear and degra­da­tion with only slight­ly longer res­i­dence time, con­sis­tent­ly high qual­i­ty, even with the most demand­ing PET com­po­si­tions.

MAS is com­mit­ted to deliv­er­ing world-class recy­cling solu­tions and redefin­ing indus­try stan­dards through ground­break­ing extru­sion tech­nol­o­gy. Our prod­ucts stand for unmatched tech­no­log­i­cal excel­lence, dri­ving per­for­mance, effi­cien­cy, and sus­tain­abil­i­ty to the next lev­el. Let our experts show you what’s pos­si­ble: expe­ri­ence tai­lored con­sul­ta­tion and dis­cov­er how MAS can ele­vate your recy­cling oper­a­tion to new lev­els.