Model association in sequelize [erro]{ this.name}.hasMany called with something that's not a subclas

//Removed this import because is not an object of Model it's a definition
module.exports = (sequelize, DataTypes) => {
  const Fator = sequelize.define('Fator', {
    descricao: DataTypes.STRING
  }, {});
  Fator.associate = function(models) {
      Fator.hasMany(models.Sub_Fator, {//Change to this instead of Sub_Fator
        foreignKey: 'fatorId',
        as: 'fatores'
    });
  };
  return Fator;
};

The reason is Because you define the model here, but then in your models/index.js or something like that you have to import it to generate an object model, this is just a model definition and it's not a SubClass of Sequelize.Model.

PS: Your index should something like this if you generated sequelize in your project:

'use strict';

var fs        = require('fs');
var path      = require('path');
var Sequelize = require('sequelize');
var basename  = path.basename(module.filename);
var env       = process.env.NODE_ENV || 'development';
var config    = require(__dirname + '/../config/server-config.json')[env];
var db        = {};

if (config.use_env_variable) {
  var sequelize = new Sequelize(process.env[config.use_env_variable]);
} else {
  var sequelize = new Sequelize(config.database, config.username, config.password, config);
}

fs
  .readdirSync(__dirname)
  .filter(function(file) {
    return (file.indexOf('.') !== 0) && (file !== basename) && (file.slice(-3) === '.js');
  })
  .forEach(function(file) {
    var model = sequelize['import'](path.join(__dirname, file));
    db[model.name] = model;
  });

Object.keys(db).forEach(function(modelName) {
  if (db[modelName].associate) {
    db[modelName].associate(db);
  }
});

db.sequelize = sequelize;
db.Sequelize = Sequelize;

module.exports = db;