{"id":39024,"date":"2026-03-01T12:00:00","date_gmt":"2026-03-01T04:00:00","guid":{"rendered":"https:\/\/zetarmold.com\/?p=39024"},"modified":"2026-04-04T10:09:41","modified_gmt":"2026-04-04T02:09:41","slug":"ajuster-les-marques-de-flux-des-produits-de-moulage-par-injection","status":"publish","type":"post","link":"https:\/\/zetarmold.com\/fr\/ajuster-les-marques-de-flux-des-produits-de-moulage-par-injection\/","title":{"rendered":"Comment ajuster les produits de moulage par injection avec des marques d'\u00e9coulement"},"content":{"rendered":"
\n Principaux enseignements<\/strong>
\n +10\u201315%
\n \u2013 Raising melt temperature 10\u201320\u00b0C and mold temperature 10\u201315\u00b0C above baseline is the most reliable process-level fix for flow marks.
\n \u2013 Gate size, location, and type account for 60% of persistent flow mark problems that can’t be solved through process optimization alone.
\n \u2013 A systematic approach\u2014adjusting temperature first, then speed, then pressure, then mold design\u2014resolves flow marks efficiently without excessive trial and error.\n<\/div>\n

What Exactly Are Flow Marks and Why Do They Matter?<\/h2>\n

Flow marks are visible surface imperfections on injection molded parts that appear as wavy lines, ripple patterns, or bands of slightly different color or gloss. They form when the advancing melt front cools unevenly against the mold wall, creating a wrinkled or folded skin that gets frozen into the final part surface. In our factory, flow marks rank among the top three cosmetic defects that cause part rejections\u2014particularly for consumer-facing products where surface appearance is critical.<\/p>\n

\n \"Common
Flow marks are a common surface defect in injection molding<\/figcaption><\/figure>\n

While flow marks rarely affect part structural integrity, they make products look unfinished and unprofessional. For automotive interior panels, consumer electronics housings, and medical device enclosures, even minor flow marks can trigger quality rejections. Understanding their root cause\u2014the interaction between melt front velocity<\/a>1<\/a><\/sup>, temperature, and mold surface\u2014is the first step toward elimination.<\/p>\n

How Does Melt Temperature Affect Flow Mark Formation?<\/h2>\n

Melt temperature is the single most influential process parameter for flow marks. When the melt temperature is too low, the plastic skin solidifies prematurely against the mold wall, creating drag and wrinkle patterns as the still-flowing core pushes the solidified skin forward. We’ve found that a 10\u201320\u00b0C increase in melt temperature eliminates flow marks in roughly 50% of cases without any other changes.<\/p>\n

\n \"Injection
Melt temperature control is critical for preventing flow marks<\/figcaption><\/figure>\n\n\n\n\n\n\n\n\n\n\n
Mat\u00e9riau<\/th>\nStandard Melt Temp (\u00b0C)<\/th>\nRecommended Temp to Reduce Flow Marks (\u00b0C)<\/th>\nMaximum Safe Temp (\u00b0C)<\/th>\n<\/tr>\n<\/thead>\n
ABS<\/td>\n220\u2013240<\/td>\n240\u2013260<\/td>\n270<\/td>\n<\/tr>\n
PC<\/td>\n280\u2013300<\/td>\n300\u2013320<\/td>\n330<\/td>\n<\/tr>\n
PP<\/td>\n200\u2013230<\/td>\n230\u2013250<\/td>\n270<\/td>\n<\/tr>\n
PMMA<\/td>\n220\u2013240<\/td>\n240\u2013260<\/td>\n270<\/td>\n<\/tr>\n
PA6<\/td>\n240\u2013260<\/td>\n260\u2013280<\/td>\n290<\/td>\n<\/tr>\n
POM<\/td>\n190\u2013210<\/td>\n200\u2013215<\/td>\n220<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

We always increase temperature in 5\u00b0C increments and evaluate 10 shots at each level. Going too high risks material degradation, yellowing, or increased marques d'\u00e9vier<\/a>2<\/a><\/sup> due to lower melt viscosity during packing.<\/p>\n

\n

<\/svg> “Lowering the melt temperature helps reduce flow marks by slowing down the plastic flow.”<\/b>Faux<\/span><\/p>\n

Lower melt temperature actually makes flow marks worse. When the melt is cooler, it solidifies faster against the mold wall, creating a thicker skin that wrinkles and drags as the core flow pushes it forward. Increasing melt temperature keeps the plastic fluid longer, allowing smooth, uniform skin formation.<\/p>\n<\/div>\n

\n

<\/svg> “Melt temperature is the single most important process parameter for controlling flow marks in injection molding.”<\/b>Vrai<\/span><\/p>\n

Among all adjustable process parameters, melt temperature has the most direct effect on flow mark formation. Higher melt temperature reduces viscosity, delays skin solidification, and improves melt front uniformity\u2014all of which directly prevent the premature cooling that causes flow marks.<\/p>\n<\/div>\n

How Does Mold Temperature Influence Surface Quality?<\/h2>\n

Mold temperature works in tandem with melt temperature to control how quickly the plastic skin forms. A higher mold temperature slows the cooling rate at the melt-mold interface, giving the plastic surface time to form smoothly rather than wrinkling. In our experience, combining melt temperature increase with mold temperature increase provides the best results.<\/p>\n

\n \"Injection
Mold cooling system directly affects surface quality<\/figcaption><\/figure>\n\n\n\n\n\n\n\n\n\n
Mat\u00e9riau<\/th>\nStandard Mold Temp (\u00b0C)<\/th>\nRecommended for Flow Mark Reduction (\u00b0C)<\/th>\nCycle Time Impact<\/th>\n<\/tr>\n<\/thead>\n
ABS<\/td>\n40\u201360<\/td>\n60\u201380<\/td>\n+5\u201310%<\/td>\n<\/tr>\n
PC<\/td>\n80\u2013100<\/td>\n100\u2013120<\/td>\n+8\u201315%<\/td>\n<\/tr>\n
PP<\/td>\n20\u201350<\/td>\n50\u201370<\/td>\n+5\u20138%<\/td>\n<\/tr>\n
PMMA<\/td>\n50\u201370<\/td>\n70\u201390<\/td>\n+10\u201315%<\/td>\n<\/tr>\n
PA6<\/td>\n60\u201380<\/td>\n\u2014 Augmentez de 3 \u00e0 5 bars. Effectuez 20 tirs pour \u00e9valuer la coh\u00e9rence.<\/td>\n+5\u201310%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The trade-off is cycle time. Every 10\u00b0C increase in mold temperature adds roughly 3\u20135% to the cooling phase. For high-volume production, we balance surface quality against productivity by finding the minimum mold temperature that eliminates flow marks\u2014often 10\u201315\u00b0C above the standard setting is enough.<\/p>\n

What Injection Speed Profile Works Best for Flow Mark Prevention?<\/h2>\n

Injection speed determines how fast the melt front advances through the cavity. For flow marks, faster is generally better\u2014a fast-moving melt front has less time to cool and wrinkle before the cavity fills. However, the speed profile matters more than the overall speed.<\/p>\n

\n \"Injection
Injection speed profiling optimizes melt flow for surface quality<\/figcaption><\/figure>\n

We use multi-stage injection speed profiles to address flow marks:<\/p>\n