injection molding company in Spain


Considerations of design about injection molding

Many times we receive a drawing with demanding tolerances, a 3D design that turn on all alarms, for example  big accumulation of mass, with paralelism, perpendicularity or flatness in raw materials like polyamide with high percent of glass fiber. By this reason, we think it is necessary to bear in mind some considerations about design of  injection molding based on more than 25 years of knowledge, that probably it could be of help.

In ZATEC we can advise to customer collaborating in this first phase of design, checking the feasibility analysis to optimize the design of piece, according to adequate raw material depending onf inal application and our process of injection molding, to reduce the investment if it is possible. As you can read as follow, we have remarked some examples about it:


although sometimes it is not possible to avoid changes of thickness, is very important to have homogeneus thickness without sudden cahnges always it will be possibe. An irregular thickness could generate problems like deformations due to differences of shrinkage in the mentioned thickness, or sink marks in the opposite face.

Sharp Edges,

the sharp edges are stress concentrations (Kc) weakening the piece. Although we can do radii in some areas could complicate the mold, also we improve the design considerably.  It is necessary to take acocunt the big accumulation of mass in the perimeter when we round this area. A good example is a plastic part like a box, and the barrel efect.


If we want a rigid piece, it is better to add nerves like reinforcement than increase the thickness. It is very important to bear in mind the crosses of nerves due to possible accumulation of mass, that as you know, this accumulation can generate asthetic defects. In areas with flat surfaces, besides of mentioned nerves, it is necessary to take account the cooling in mold with variations of temperatute, location and size of injection gate(s) and the chosen of adequate engineering plastic based on final application.

Towers and spigots

It should be designed to avoid big accumulation of mass, bubbles… theredore the important consideration is the difference between exterior radius and inner radius.

considerations about design of injection molding


if it is possible, avoid the thread’s pitch too thin.  In case of female thread, avoid the fillet ends up to final of piece by possible breaks. In case of  male threads demolded by sliders, can be stopped at height of union line, avoiding if it is possible the problem of wear. As we have mentioned, is important to avoid the sharpd edges with weak mechanical properties, by this reason a good option is to reduce them.

Parts with Inserts

The inserts must not weakening the around material, by this reason the optimum thickness of around material of insert, it must be verified. The shrinkage of plastic on the metal can generate an overflow. This overflow could be removed, doing a ribbed uniform and crossed in the insert part.  Based on our knowledge, it is recommended to heat the insert before injectioning.

If we can help you with a project of plastic part, based on our expertise of engineering plastics and injection molding, do not hesitate to contact us like company of technical plastic injection located in Muel, Zaragoza (Spain), where we can collaborate actively with our customers.


ZATEC wishes you Merry Christmas

ZATEC wishes to all peopele who is in contact us, directly or indirectly, Merry Christmas and a Happy New Yeear .                           

This 2020 has been a complicated year, but we should look ahead, improving each day and adapting  to this new scenario with Covid-19.

We would like to thank the effort of our workers, the support from all suppliers and specially to customers that continue trusting in Zatec despite of Covid situation.

We know the essential is invisible to our eyes, by this reason we want to wish you a Merry Christmas and mainly a good health in this new year 2021.


Situation in Zatec about COVID-19

Today is the star theme in the Tv news with current alarm state communicated by the Spanish Government.

Several weeks ago, we saw this situation far away in China and his quick spread have been the same in Spain or even further. In Zatec we read each day bad news due to temporal closure of companies, mainly in automotive market due to mentioned COVID-19.

Internally in ZATEC, we have taken several safety measures and continue analyzing future proposals from workers to avoid, if it is possible, the quick spread, keeping the security in our facility:

  • Maximum 3 workers in each costume (male and female), to respect the minimum distance between workers of aboout 1 meter in the change of shift.
  • Maximum 1 worker in the break cofee area.
  • Of course,  clean the hand with soap more times than usual. Mainly after/before clocking in.
  • More cleanliness in switches, handles, knobs….
  • To use glovees according to each workstation.
  • Flexibility in the shifts, prioritizing the workers with sons and dependent family members.
  • There will be not visits,  from Zatec to Customers/suppliers and from out to Zatec. Except to in execptional cases like repairs with the adequate safety measures.
  • The last point is very important to transporters. The drivers must not enter to warehouse.
  • Bear in mind the possibility to work from house with portable PC in depending on some cases like office.

Anyway, besides of sanitary point of view, that obviously this is the most important, this situation COVID-19 is producing an elevated economical impact in the industry. In fact, there iare some examples in automotive like Seat, VW, Nissan, PSA, Ford, Mercedes… and therefore several companies like Tier-1 1, similar than a house of cards  which is collapsing. Everything is connected.   This is a chain.  Nevertheless in Zatec we continue working 24 hours/ 5 days per week due to we have not positive cases of Covid-19 and we hace still customers working despite of this complicated situation. They need our plastic components of injection molding but we understand this situation could be different tomorrow, waiting the next news about this pandemic.

By this reason we are evaluating our situation in each moment to analyze the best option for our customers and workers day to day.

There are a lot of type of customers, and the critical point at this moment is the direct communicationin both directions to help us like “partners” and not only like acomercial relationship.  Sometimes, there are plastic parts in the transport without posibility to download in the destination due to temporal closure of some companies and this is other unnecesary extra problem. We expect this situation finished as soon as possible but we understand there is a long way to walk, yet. Then, we will adapt at this new moment, and we will continue working to improve and supplying plastic parts of injection molding for different markets like Automotive, being more flexibles in our production based on our know how.

We wish you good healthy to enjoy of working again, with at least relative normality.

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