Industry News

How to control the color difference of injection products?

2018-12-24
Tlhahiso e kholo: Phapang ea mebala ke bokooa bo tloaelehileng ka ho entša ente. Ke ntho e tloaelehileng hore mochine o sebetsang ka majoe o kenngoe ka li-batches ka lebaka la phapang ea mebala ea likarolo tse tšoanang. Ho na le mabaka a mangata a amang phapang ea mebala, ho kenyeletsa le resin e tala, 'mala oa Masterbatch (kapa' mala o motsoako).

Color difference is a common defect in injection moulding. It is not uncommon for injection moulding machines to be scrapped in batches because of the color difference of matching parts. There are many factors affecting the color difference, such as raw resin, Color Masterbatch (or color powder), mixture of color masterbatch and raw material, injection molding process, injection moulding machine, mould and so on. Because it involves a wide range of aspects, the color difference control technology is also recognized as one of the more difficult technologies to master in injection moulding. In the actual production process, we generally control the color difference from the following six aspects.



1. Tlosa tšusumetso ea mochine oa ho kenya mochine le hlobo



To choose the injection machine with the same capacity as the injection product, if the injection machine has the problem of material dead angle, it is better to replace the equipment. For the color difference caused by the casting system and the exhaust groove of the die, it can be solved by the maintenance die of the corresponding part of the die. It is necessary to solve the problems of injection moulding machines and moulds in order to organize production and reduce the complexity of the problem.



2. Eliminate the influence of raw resin and colour masterbatch



Control of raw materials is the key to completely solve the problem of chromatic aberration. Therefore, especially in the production of light-colored products, we can not ignore the obvious influence of different thermal stability of raw resin on the color fluctuation of products.



In view of the fact that most injection moulding manufacturers do not produce plastic masterbatches or color masterbatches themselves, attention can be focused on production management and raw material inspection. That is, to strengthen the inspection of raw materials into storage; to produce the same product, the same manufacturer, the same brand masterbatch and color masterbatch should be adopted as far as possible;



For masterbatches, we have to carry out spot check and test before mass production, not only with the last proofreading, but also in this comparison, if the color difference is not big, we can consider qualified, just as the batch masterbatches have slight color difference, we can re-mix the masterbatches and then use them to reduce the color difference caused by the uneven mixing of the masterbatches themselves. At the same time, we also need to focus on testing the thermal stability of raw resins and masterbatches. For those with poor thermal stability, we suggest that manufacturers change.



3. Eliminate the influence of uneven mixing of masterbatch and Masterbatch



Ho kopanya hampe ha li-plastiki tse sebetsang hantle ka li-masterbatches ho ka etsa hore 'mala oa lihlahisoa o fetohe. Ha masterbatch le masterbatch li kopantsoe ka tsela e lekanang mme li fepeloa ka holimo ka ho pota-potiloe ka letsoho, masterbatch e hlaseloa habonolo leboteng la holimo ka lebaka la motlakase o tsitsitseng, o tla etsa hore phetoho ea masterbatch e be ka potoloho e entsoeng ka ente, e leng se hlahisang 'mala phapang.



Boemo bona bo ka rarolloa ka ho kenya lihlahisoa tse tala ka li-hoppers ebe joale lia li kopanya ka letsoho. Bakeng sa tlhahiso ea lihlahisoa tse seng tsa fere ka ho eketsa 'mala o motsoako, tsela e sebetsang ka ho fetisisa ke ho se sebelise mochini o tsoelang pele, empa ho sebelisa sesepa se chesang sa moea le mokhoa oa ho fepa ka mokhoa oa ho thibela mebala e bakoang ke ho arohana ha' mala oa phofo le masterbatch.



4. The effect of reducing barrel temperature on chromatic aberration



Ha ho etsoa tlhahiso, hangata ho kopana le hore mocheso oa molamu o fetoha ka mokhoa o tsotehang ka lebaka la ho hlōleha ha leseli la ho futhumatsa kapa ho chesa ha nako e sa laoleheng ha karolo e laolang ho futhumatsa, e leng se hlahisoang ke kromatic aberration. Ho senyeha ha chromatic ho bakoang ke mofuta ona oa mabaka ho bonolo ho ahlola. Ka kakaretso, ts'ebetso ea chromatic e bakoang ke ho hlōleha ha ho futhumatsa ka hare ho tsamaisana le ts'ebetso ea pente ea seaparo se sa tšoaneng, ha nako e telele e sa laoleheng ea ho laola mocheso e atisa ho tsamaea le sehlahisoa sa khase, ho senyeha ha sekhahla esita le ho pheha. Ka hona, ho hlokahala hore ho hlahlojoe karolo e futhumatsang khafetsa tlhahiso, 'me u e nke le ho e lokisa ka nako eo karolo ea futhumatsang e senyehileng kapa e sa laoleheng, e le ho fokotsa menyetla ea mofuta ona oa ts'ebetso ea chromatic.



5. Fokotsa tšusumetso ea ho etsa phetoho ea ente



When adjusting the injection process parameters for Non-chromatic reasons, the injection temperature, back pressure, injection cycle and the amount of colour masterbatch should not be changed as far as possible. At the same time, the influence of the change of process parameters on the colour should be observed. If the colour difference is found, it should be adjusted in time.



As far as possible, avoid using injection moulding technology with high injection speed, high back pressure and other factors that cause strong shear effect, and prevent color difference caused by local overheating or thermal decomposition. Strictly control the temperature of each heating section of the barrel, especially the heating part of the nozzle and the adjacent nozzle.



6. Master the influence of barrel temperature and masterbatch quantity on product color change



Before adjusting the color difference, it is necessary to know the trend of product color changing with temperature and masterbatch. Different masterbatches have different color changing rules with the change of temperature or quantity of masterbatches. The changing rule can be determined by the process of color test.



Ha ho khonehe ho fetola phapang ea mebala ka potlako ntle le hore puso e fetohang ea 'mala oa masterbatch e tsejoe, haholo-holo ha ho sebelisoa masterbatch e ncha.